The 20th Book - Dermatology

Additional context

This document delves into the fundamental building blocks of dermatology, specifically the layers of the epidermis. Understanding these layers is crucial in dermatology as they form the primary barrier between our bodies and the external environment. This field of study is vital for diagnosing and treating a vast array of conditions, from common dry skin and acne to more serious diseases like skin cancer and autoimmune disorders that manifest on the skin. The document's focus on the epidermis's cellular structure and its differentiation process builds upon centuries of histological research, dating back to the development of the microscope. Early dermatologists meticulously observed and described skin tissues, laying the groundwork for modern understanding. This work, therefore, is a continuation of that legacy, providing foundational knowledge that informs clinical practice and research into skin diseases.

the 20th BOOK-Dermatology Chapter 1: Dermatology Basics

Layers of the Epidermis

Mnemonic

“Come Let's Get Sun Burned” (from above downwards)

Corneum leads to Lucidum leads to Granulosum leads to Spinosum leads to Basale

Image summary: This figure is a diagrammatic illustration. It depicts the various layers of the skin, showing the transition from the deep basal layer of columnar cells to the superficial layers of flattened, dead cells. The diagram includes a mnemonic phrase aligned with the vertical layers of the epidermis. The illustration demonstrates that skin cells undergo a process of differentiation and flattening as they migrate from the bottom layer toward the surface, eventually forming a protective outer barrier.

Image summary: This is a schematic diagram. It depicts a layered cellular structure consisting of multiple tiers of cells with varying shapes and sizes, topped by flat surface layers and anchored to a base. The cells are interconnected by thin fiber-like structures that span across the different layers. The diagram illustrates a stratified tissue organization where cells are organized in a hierarchical fashion, suggesting a protective or structural barrier with integrated communication or adhesion mechanisms between the layers.

Table summary: The table outlines the distinct characteristics and primary functions of the various layers of the epidermis, detailing the cellular composition and specific markers of the stratum corneum, lucidum, granulosum, spinosum, and basale, while noting the clinical implications of defects in these layers.

• Normal: 42 to 75 days (basal layer to stratum corneum to shed off)

• Psoriasis: 4 to 7 days (approximately one tenth of normal) arrow rapid proliferation arrow silvery white scaling

Acantholytic Cells and Tzanck Smear

• Acantholytic cell = keratinocyte separated due to damage of desmosomes to round cell with hyperchromatic nucleus and perinuclear halo

• Identified by Tzanck smear

Table summary: The table categorizes various diseases based on their underlying causes, including autoimmune, bacterial, viral, and genetic origins.

Image summary: This figure is a photomicrograph of a biological sample. It displays a collection of cells with varying sizes and shapes, featuring a prominent cell indicated by an arrow that exhibits a large nucleus. The presence of these enlarged and irregularly shaped cells suggests a pathological condition, indicating cellular atypia or malignancy.

Dermatopathological Terms

Table summary: This table lists specific histopathological findings and their descriptions, associating each characteristic with its corresponding skin condition, primarily distinguishing between Psoriasis, Lichen Planus, and Mycosis fungoides.

4 Definitions

Definition 1: Mycosis fungoides: A type of cutaneous T-cell lymphoma, a cancer of the skin that begins with lymphocytes.

Definition 2: Pautrier's microabscess: Small collections of lymphocytes found in the epidermis, characteristic of mycosis fungoides.

Definition 3: Psoriasis: A chronic autoimmune disease that causes the rapid buildup of skin cells, leading to scaling on the skin's surface.

Definition 4: Munro's microabscess: Collections of neutrophils found in the stratum corneum, characteristic of psoriasis.

Cross Mnemonic: M for P, P for M Mycosis fungoides leads to Pautrier's microabscess Psoriasis leads to Munro's microabscess

Histopathology of Psoriasis

Image summary: This figure consists of three photomicrographs showing histopathological sections of skin tissue. The images display various pathological features including hyperkeratosis, parakeratosis, thin suprapapillary epidermal plates, club shaped rete ridges, spongiform pustules of Kogoj located in the spinous or granular layer, Munro microabscesses within the stratum corneum, and dilated blood vessels accompanied by surrounding inflammation. These combined histological findings are characteristic indicators used to diagnose Lichen Planus.

Table summary: The table outlines the histopathological characteristics of the skin layers, highlighting epidermal thickening and neutrophil accumulation in the upper layers, structural changes to the rete ridges and dermal papillae, and the physiological basis for the Auspitz sign.

Image summary: This figure is a histopathological micrograph. It displays a tissue sample of Lichen Planus, highlighting specific pathological features including orthokeratosis, hypergranulosis, Civatte bodies, the Max-Joseph space, and a lichenoid band of inflammation. The image demonstrates a dense inflammatory infiltrate concentrated at the dermal-epidermal junction, accompanied by epidermal thickening and the presence of apoptotic keratinocytes, which are characteristic markers of this inflammatory skin condition.

Table summary: The histopathological characteristics of Lichen Planus are detailed across various skin layers, highlighting thickening of the stratum corneum and granular layer, along with a band-like lymphocytic infiltrate at the dermoepidermal junction that leads to basal cell apoptosis and the formation of Max-Joseph spaces.

Cells of the Epidermis

5 Definitions

Definition 1: Keratinocyte: The main type of cell found in the epidermis, responsible for producing keratin, a tough protein that protects the skin.

Definition 2: Langerhans cells: Immune cells found in the epidermis that play a role in detecting and fighting off pathogens.

Definition 3: Melanocytes: Cells in the epidermis that produce melanin, the pigment responsible for skin and hair color.

Definition 4: Merkel cells: Cells in the epidermis that are involved in touch sensation.

Definition 5: Stratum basale: The deepest layer of the epidermis, where new skin cells are produced.

Principal cell: Keratinocyte (majority of epidermal cells). Other 3 cells: Langerhans cells, Melanocytes, Merkel cells “Munni ko base pasand hai” Melanocytes and Merkel cells are present in the stratum basale Langerhans Cell — Electron Microscopy

Image summary: This is a labeled anatomical diagram. The figure illustrates the layered structure of the epidermis and its transition into the dermis, identifying various strata and specialized cell types. The diagram shows that the skin is composed of multiple distinct layers, with the stratum basale at the deepest level and the stratum corneum as the outermost layer. It can be inferred that as cells move from the basal layer toward the surface, they undergo a transformation from living keratinocytes to dead keratinocytes. Additionally, the presence of various specialized cells, such as melanocytes, Merkel cells, and Langerhans cells, indicates that the epidermis performs multiple functions including sensory perception, immune defense, and pigmentation.

Table summary: The table outlines the origin, anatomical location, biological function, associated malignancies, and diagnostic markers for three distinct skin cell types: Langerhans cells, melanocytes, and Merkel cells.

Image summary: This figure is a biological schematic diagram. It illustrates the characteristics, origin, and lifecycle of a specific immune cell within the layers of the skin, spanning from the dermis through the various strata of the epidermis. The diagram highlights the cell's dual nature by categorizing its attributes into macrophage features and dendritic cell features, while showing its relationship to blood vessels, lymphatic vessels, and the surrounding tissue environment. Based on the diagram, the cell exhibits a hybrid phenotype, combining the phagocytic and self-renewal capabilities of macrophages with the antigen presentation and lymph node migration capabilities of dendritic cells. The cell's development is dependent on tissue-derived signals and embryonic origins, and its population can be supplemented by monocytes from the blood during inflammatory responses.

Image summary: This figure is a biological diagram. It illustrates the structural relationship between a melanocyte and surrounding keratinocytes within the skin layers, specifically showing the basement membrane and the underlying dermis. The diagram depicts the process of melanin pigment being transported via melanosomes from the melanocyte into the adjacent keratinocytes. It can be inferred that melanocytes serve as the primary source of pigment for the skin and that they distribute this pigment to multiple surrounding cells through specialized extensions.

• Birbeck granules: tennis racquet-shaped to seen only under electron microscopy (not light microscopy)

• Langerhans cells have dendritic processes in the stratum spinosum

Image summary: This is a transmission electron micrograph. The image displays a cross-section of cellular structures, specifically showing membrane-bound organelles and elongated, tubular connections between them. These tubular structures exhibit internal striations or layered patterns. The presence of these specialized junctions indicates a high degree of connectivity and structural organization between the organelles, suggesting a mechanism for the transport of materials or signaling between different compartments of the cell.

Epidermal Melanin Unit

- 1 melanocyte transfers melanosomes and melanin pigment to 36 adjacent keratinocytes

• This unit = Epidermal Melanin Unit (ratio 1:36)

Lines in Dermatology

Definition

Blaschko's Lines: Lines on the skin representing the developmental patterns of cellular mutation or migration.

Blaschko's Lines (Q)

• Represent pathway of epidermal cell migration during embryonic development

- Do not correspond to dermatomes, lymphatics, arteries, veins, or nerves

- not visible under normal circumstances leads to seen only in certain diseases

- Do not cross the midline (midline demarcation present)

Table summary: This table outlines the specific configuration of patterns associated with different body regions, showing a distinct mapping between each anatomical area and its corresponding shape.

Definition

Incontinentia Pigmenti: A genetic disorder that affects the skin, hair, nails, teeth, and central nervous system.

Clinical Example: Incontinentia Pigmenti

• X-linked dominant inheritance leads to Nemo gene mutation

• Lesions follow Blaschko's lines

Langer's Lines (Lines of Cleavage / Relaxed Skin Tension Lines)

- Correspond to natural orientation of collagen fibers within the dermis (Q)

• Surgical incisions should be given along Langer's lines leads to healing without scarring

• Cross the midline (no midline demarcation) – unlike Blaschko's lines

• Pityriasis rosea leads to Christmas tree distribution of lesions along Langer's lines

Image summary: This figure consists of a series of anatomical diagrams. The content displays a detailed close up of a human face alongside full body views from both the front and back, all featuring a network of flowing, parallel lines that map across the skin's surface. These illustrations suggest a systematic mapping of tension lines or surface patterns across the human body, indicating that these structural alignments are consistent and continuous from the facial features across the entire torso and limbs.

High Yield

Blaschko's vs Langer's Lines

• Represent: Blaschko = Epidermal cell migration pathway;

• Midline: Blaschko = Do not cross midline; Langer = Cross the midline

• Disease example: Blaschko = Incontinentia pigmenti; Langer = Pityriasis rosea

• Surgical relevance: Blaschko = None; Langer = Incisions along for scar-free healing

Wood's Lamp

• Handheld device to emits light of wavelength 365 nanometers (number of days in a calendar year)

- Filter: 9% Nickel Oxide + Barium Silicate (mnemonic: no B.S

Table summary: The table lists various skin conditions and their corresponding characteristic fluorescence colors observed under specific lighting.

Therapeutic Modalities

Cryotherapy

Table summary: This table outlines the parameters for a cryotherapy procedure, specifying the cooling agent used, the operating temperature, the biological mechanism leading to tissue death, and the clinical indications for its application.

Phototherapy

Table summary: The table compares two phototherapy modalities, detailing their respective wavelength ranges and clinical applications, highlighting the use of a photosensitizer in one method to enhance skin penetration.

Definition

Vesiculobullous: Relating to or characterized by vesicles (small fluid-filled blisters) and bullae (larger blisters).

Chapter 2: vesikulo-bullous Disorders

Pemphigus Group (Intraepidermal Blistering)

P.Y.T gold

• Pemphigus equals blister inside the epidermis leads to intraepidermal blistering disorder

• Bullae are flaccid (Q) to thin epidermal roof to acantholysis present

• Nikolsky's sign: Positive (Q) arrow superficial layers easily removed

Pemphigus Vulgaris (Q)

Image summary: This is a clinical photograph. The image shows a close up view of a person's teeth and gums, specifically highlighting a significant swelling and inflammation of the gingival tissue in the lower jaw area. The affected area appears enlarged and irritated compared to the surrounding healthy gum tissue. It can be inferred that the patient is suffering from a localized periodontal or soft tissue pathology, such as a gingival hyperplasia or a pyogenic granuloma, requiring dental intervention.

Image summary: This is a clinical photograph. The image displays a close up view of the oral cavity, specifically focusing on the inner cheek and gum area adjacent to the teeth, which shows significant tissue erosion and ulceration. The presence of extensive mucosal breakdown and irregular surface lesions suggests a severe inflammatory process or a pathological condition affecting the soft tissues of the mouth.

Image summary: This is a clinical photograph. The image displays a close up view of human skin featuring several raised lesions. One lesion is significantly larger and more prominent with a textured, folded surface, while others are smaller and appear as shallow pits or crusts. The presence of these varied skin growths suggests a dermatological condition characterized by the formation of papules and erosions.

Image summary: This is a clinical photograph. The image shows a person's skin with extensive areas of redness, blistering, and peeling. There are several large, fluid-filled blisters and regions where the top layer of skin has sloughed off, exposing raw, moist tissue underneath. The distribution of the lesions is widespread across the visible area of the torso. The presence of widespread epidermal detachment and bullae indicates a severe inflammatory or autoimmune skin condition characterized by significant loss of skin integrity.

Table summary: The table outlines the diagnostic and therapeutic characteristics of a condition, highlighting its preference for specific antigens, its suprabasal split level, and the resulting clinical presentation of flaccid bullae and mucosal ulcerations. It further details the distinct histological row of tombstone appearance and the characteristic fishnet pattern seen in direct immunofluorescence, concluding with a treatment hierarchy favoring steroids followed by Rituximab.

Image summary: This is a clinical photograph. The image displays a section of skin where the top layer has been peeled away, leaving behind a raw, exposed area, with an arrow pointing to the edge of the detached skin. The presence of this skin detachment upon application of slight pressure or friction indicates a positive Nikolsky sign, which suggests a loss of adhesion between skin layers often associated with severe blistering diseases.

Image summary: This is a photomicrograph of a histological tissue section. The image displays a cross-section of skin showing the epidermis and the underlying dermis, with a distinct separation or cleft forming between these two layers. The separation indicates a loss of adhesion at the dermal-epidermal junction, which is characteristic of blistering conditions.

Image summary: This figure consists of a side-by-side comparison between a fluorescence microscopy image and a photograph. The left side displays a biological tissue sample showing a network of cellular boundaries, while the right side shows a synthetic hexagonal wire mesh. The comparison illustrates a structural similarity between the biological cellular organization and the geometric pattern of the man-made mesh, suggesting that the natural tissue exhibits a honeycomb-like architecture.

Definition

Pemphigus: A group of rare autoimmune diseases that cause blistering of the skin and mucous membranes.

Drug-Induced Pemphigus

- Drugs that can induce pemphigus: D-penicillamine, Captopril, Rifampicin

Definition

Bullous Pemphigoid: An autoimmune blistering disease that affects the skin, typically causing large, tense blisters.

Pemphigus Foliaceus Bullous pemp-fih-goyd subepidermal blistering

Table summary: The table outlines the characteristics of a condition targeting Desmoglein-1, noting that the split occurs in the subcorneal layer where the target antigen is most concentrated, resulting in skin erosions and crusting while leaving the mucosa unaffected.

Image summary: This is a clinical photograph. The image shows a close-up view of human skin featuring multiple fluid-filled blisters of varying sizes on an inflamed, red base. Some areas show ruptured blisters with exposed raw skin. The presence of tense bullae and widespread erythema suggests an acute inflammatory or autoimmune blistering skin condition.

• Subepidermal blistering leads to complete roof by all epidermal layers

• Bullae are tense (Q) (opposite of pemphigus)

• Nikolsky's sign: Negative to no acantholysis

• Tendency to heal leads to lesions heal nicely (opposite of pemphigus)

• Associated with intense itching

• Biopsy shows prominent eosinophils

Table summary: The table outlines the diagnostic characteristics of a specific condition, detailing its target antigens, the nature of its pathology at the dermoepidermal junction, and the positive results observed during direct immunofluorescence and salt split testing.

Image summary: This figure is a photomicrograph of a histological tissue section. The image displays a cross-section of skin, showing the epidermal layer with its characteristic stratified squamous epithelium and the underlying dermal layer containing connective tissue and various cellular infiltrates. The presence of dense inflammatory cell clusters within the dermis and the separation between the epidermis and dermis indicate a pathological condition characterized by inflammation and dermal-epidermal detachment.

Image summary: This figure is a fluorescence microscopy image. It displays a biological tissue section where specific markers are highlighted through fluorescent staining, showing a distinct boundary between a surface layer and the underlying tissue. The image reveals a continuous, linear deposition of fluorescence along the basement membrane zone, indicating a concentrated presence of targeted antigens or antibodies at this interface. This pattern suggests a localized accumulation of immune complexes or proteins, which is characteristic of certain autoimmune blistering diseases.

Chronic Bullous Dermatosis of Childhood

Image summary: This is a clinical photograph. The image shows a patch of inflamed skin characterized by redness and the presence of multiple small, fluid-filled blisters. These vesicles are clustered together and vary in size, appearing on an erythematous base. The distribution of the blisters suggests a localized skin reaction or infection, where the skin is irritated and exhibiting a blistering response.

- Also called Linear IgA Bullous Dermatosis of childhood

- Classic sign: "String of pearls" / "Cluster of jewels" / "Crown of jewels" to new blisters ring around old healing blisters

• Lesions predominantly on periodificial skin (Q)

- · D.I.F: Linear deposition of IgA

• Treatment: Dapsone (Q)

• Mnemonic: "Crown of jewels" arrow visualize crown of ElizagAbeth arrow remember IgA

Dermatitis Herpetiformis

Image summary: This figure is a composite of clinical photographs and immunofluorescence microscopy images. The clinical images display various skin lesions, including red papules and nodules on the lower limbs and larger, raised plaques on another body area. The microscopy images show a pattern of fluorescent deposits within the skin layers. The presence of these specific skin manifestations combined with the granular deposition pattern observed in the immunofluorescence images suggests a diagnosis of a blistering or autoimmune skin condition.

• Intensely itchy red papulovesicular lesions

• Sites: extensor surfaces leads to elbows and knees

• Strongly associated with celiac disease / gluten sensitive enteropathy (Q)

Biopsy: subepidermal blister with neutrophilic infiltration in dermal papilla

· D.I.F: IgA deposition in granular fashion to “Picket fence” appearance in dermal papilla; IgA also deposited in a linear fashion

Image summary: This figure is a photomicrograph of a histological skin section. The image displays the epidermal layer on the left and the underlying papillary dermis on the right, with labels identifying neutrophilic granulocytes and papillary abscesses within the dermal layer. The presence of dense clusters of neutrophilic granulocytes and the formation of papillary abscesses indicate an acute inflammatory response occurring within the upper layer of the dermis.

Table summary: The table identifies the preferred pharmacological agent and the primary dietary intervention for treatment.

Table summary: The table provides a mnemonic to help identify gluten-rich foods that should be avoided, specifically listing barley, rye, oats, and wheat.

Epidermolysis Bullosa (Mechanobullous) — D.I.F Negative

• Genetic conditions leads to D.I.F negative (no antigen-antibody)

• Blisters from minor mechanical trauma / friction (Q)

• Exam clue: mom handling baby leads to blisters develop leads to mechanobullous

Table summary: The table categorizes different types of Epidermolysis Bullosa by their associated gene or protein defects and the specific anatomical level where the skin split occurs, showing a progression of cleavage from the epidermis down to the dermis.

Image summary: This is a clinical photograph. The image displays a human hand exhibiting severe swelling, skin thickening, and extensive scaling across the palm and fingers. The skin appears inflamed and textured with irregular patches of peeling. The overall appearance suggests a significant inflammatory or dermatological condition characterized by widespread edema and epidermal damage.

• Mitten hand deformity to distal extremities severely involved to repeated blistering to deformity

Definition

Epidermolysis Bullosa Acquisita: A rare autoimmune blistering disease that causes skin fragility and blistering, often on areas subject to friction.

Epidermolysis Bullosa Acquisita

• not genetic to autoimmune/immunobullous disorder

• Target: Type 7 Collagen (same as dystrophic E.B but autoimmune)

• Salt Split D.I.F: fluorescence on the floor (opposite of B.P which shows roof)

Definition

Salt Split Test: A laboratory test used to differentiate between types of blistering disorders by splitting the skin along different layers.

high yield Salt Split Test: Roof vs Floor Bullous Pemphigoid leads to Roof Epidermolysis Bullosa Acquisita to Floor

Image summary: This figure is a fluorescence microscopy image. It displays a cross-section of skin tissue showing a distinct linear band of fluorescence along the dermal-epidermal junction, with some staining present in the upper epidermal layers. The presence of a continuous, sharp line of fluorescence at the junction indicates the deposition of antibodies or proteins at the basement membrane zone, which is characteristic of certain autoimmune blistering skin diseases.

Darier Disease (Inherited Acantholytic) — D.I.F Negative

Image summary: This is a clinical photograph. The image displays a person's upper chest and shoulder area, showing a widespread, red, inflammatory skin rash characterized by confluent patches and smaller papules. The distribution of the rash is concentrated across the chest and extends toward the shoulder and neck. The presence of extensive erythema and skin irritation suggests an acute inflammatory dermatological condition.

Image summary: This is a clinical photograph. The image displays a close up view of a human nail and the surrounding skin, showing an abnormal growth or accumulation of material along the nail fold. The presence of thickened, irregular tissue at the edge of the nail suggests a dermatological condition, indicating a localized inflammatory response or a nail disorder.

Image summary: This is a clinical photograph. The image displays the hard palate of a patient's mouth, showing the mucosal surface between the upper dental arches. The palate exhibits widespread, small, raised nodules and an irregular, pebbly texture across the surface, indicating a systemic or localized mucosal condition.

Table summary: This table outlines the genetic, clinical, and histological characteristics of a condition caused by a calcium ATPase channel defect, highlighting its autosomal dominant inheritance, specific skin and mucosal presentations, distinct nail changes, and the absence of autoimmune markers.

Hailey-Hailey Disease (Inherited Acantholytic) — D.I.F Negative

Image summary: This is a clinical photograph. The image displays a localized area of skin inflammation characterized by a raised, textured plaque with irregular borders. The affected region shows significant scaling and thickening of the skin surface. The appearance is consistent with a chronic inflammatory dermatosis, suggesting a condition involving epidermal hyperplasia and inflammation.

Image summary: This is a photomicrograph of a histological tissue section. The image displays a skin sample showing abnormal growth patterns within the epidermal and dermal layers, characterized by irregular projections and dense cellular infiltration. The presence of these distorted structures and the disrupted skin architecture indicate a pathological condition associated with hair follicle disorders.

Table summary: The table outlines the genetic, clinical, and histological characteristics of a specific calcium ATPase channel defect, highlighting its autosomal dominant inheritance, typical skin manifestations in flexural areas, a distinct histological appearance, and the absence of autoimmune markers.

P.Y.T gold

Classification of Alopecia

• Alopecia = loss of hair

• Two broad types: Scarring (Cicatricial) (Q) and Non-Scarring (Non-Cicatricial) (Q)

• Scarring: hair follicles completely destroyed to hair will never grow back

- Non-scarring: hair loss present but regrowth possible

Table summary: This table categorizes various causes of scarring alopecia, detailing the specific diseases and their characteristic clinical presentations. It groups these conditions into categories such as papulosquamous, granulomatous, connective tissue, infections, and other types, highlighting distinct markers like scaling, depigmentation, and the loss of eyebrows or eyelashes.

Image summary: This is a dermoscopic photograph. The image displays a close up view of the scalp showing hair follicles and the surrounding skin surface, with several small markers highlighting specific areas of interest. The presence of sparse hair distribution and specific skin patterns suggests a condition involving hair loss, indicating a diagnosis of alopecia areata based on the characteristic follicular changes observed.

Image summary: This is a clinical photograph. The image shows the top of a person's head featuring multiple patches of hair loss. These bald areas appear as smooth, skin-colored lesions surrounded by remaining hair. The distribution of the hair loss is patchy, with one large central area and smaller peripheral spots. The presence of these well-defined, non-scarring patches of alopecia suggests a condition such as alopecia areata.

Image summary: This is a clinical photograph. The image shows a close up view of a person's forehead and upper face, highlighting significant hair loss across the frontal and top regions of the scalp. The pattern of alopecia is extensive, leaving only hair on the sides and back of the head, which is characteristic of advanced androgenetic alopecia or a similar form of scalp hair loss.

Image summary: This is a clinical photograph. The image shows a close up view of a human eye and the surrounding skin of the forehead and temple area, which exhibits signs of aging such as wrinkles and hyperpigmentation. The skin appears weathered with visible fine lines and uneven skin tone, suggesting long term exposure to environmental factors.

Image summary: This is a clinical photograph. The image shows a side profile of a person's head, focusing on the forehead, temple, and hairline. There is a noticeable recession of the hairline and thinning of the hair across the top and front of the scalp. The observation indicates a pattern of hair loss, suggesting androgenetic alopecia or a similar condition characterized by receding hair and scalp exposure.

Figure d summary: This is a photomicrograph of a histological tissue section. The image displays cross sections of blood vessels surrounded by connective tissue and infiltrating inflammatory cells. The vessels exhibit significant thickening of the walls, characterized by concentric layers of smooth muscle and fibrous tissue, which results in a narrowing of the internal lumen. The presence of these structural changes and the surrounding cellular infiltration suggests a chronic inflammatory process leading to vascular remodeling and stenosis.

Non-Scarring Alopecia (Non-Cicatricial) (Q)

Table summary: The table categorizes various hair loss diseases based on their presentation patterns, distinguishing between patchy, diffuse, patterned, and systemic types, while highlighting the specific triggers and clinical characteristics associated with each condition.

Table summary: The table lists high yield medical conditions that can result in both scarring and non-scarring alopecia, specifically highlighting tinea capitis and systemic lupus erythematosus.

Alopecia Areata

Image summary: This is a clinical photograph. The image shows the scalp of an individual featuring several distinct, smooth, circular patches of hair loss. These bald areas are scattered across the crown and side of the head, contrasting with the surrounding dense hair. The presence of multiple well-defined, non-scarring patches of alopecia suggests a condition such as alopecia areata.

Image summary: This is a dermoscopic photograph. The image displays a close up view of the scalp showing several hair shafts and the underlying skin surface. Small arrows point toward a specific hair shaft that appears thinner and shorter than the surrounding healthy hairs. The presence of these miniaturized hairs suggests a process of follicular miniaturization, which is a characteristic indicator of androgenetic alopecia.

• Autoimmune condition to complete patch of hair loss

Associated with type 1 diabetes mellitus and Hashimoto's thyroiditis

Table summary: The table outlines the characteristic histological, clinical, and physical markers of the condition, highlighting specific hair morphology, the selective loss of pigmented hair over white hair, and the presence of regular nail pitting.

Image summary: This figure is a photomicrograph of a histological tissue section. It displays cross sections of blood vessels embedded within adipose tissue, characterized by large, clear vacuoles. The blood vessels exhibit significant thickening of the walls due to a dense infiltration of inflammatory cells. The presence of extensive perivascular inflammatory cell accumulation suggests a state of chronic inflammation or vasculitis within the fatty tissue.

Variants of Alopecia Areata

Image summary: This is a clinical photograph. The image displays a close-up view of a human fingernail, showing the nail plate and the surrounding cuticle and skin. The nail surface exhibits a distinct pattern of fine, grid-like depressions or pitting across the central portion of the nail plate. This appearance suggests a condition characterized by nail pitting, which is often associated with inflammatory skin disorders such as psoriasis.

Table summary: The table describes various variants of alopecia, detailing the specific patterns and locations of hair loss associated with each type.

Trichotillomania

Image summary: This is a clinical photograph. The image shows a close up view of a human scalp exhibiting areas of hair thinning and patchy hair loss. The scalp appears sparse with visible skin through the remaining hair follicles, indicating a condition of alopecia.

• Literally “hair pulling madness” to traction alopecia from constant pulling

Patchy alopecia with hairs of variable lengths (key differentiating feature)

• Involves only accessible areas to inaccessible areas spared

• Late stage: Trichobezoar formation to patient eats hair to hair ball visible in stomach on radiology

• Histology: Perifollicular hemorrhages (Q) to important differentiating point from alopecia areata

Androgenetic Alopecia

Image summary: This is a clinical photograph. The image shows the upper frontal region of a person's scalp and forehead, focusing on the hairline. There is a noticeable recession of the hairline and a significant decrease in hair density across the top of the scalp, revealing the skin beneath. The pattern suggests male pattern baldness, characterized by thinning hair and a receding frontal hairline.

Image summary: This is a photographic image. The figure displays a close-up view of a person's scalp and hair, focusing on the crown area. The image reveals significant thinning of the hair, with the scalp clearly visible through the remaining strands. This pattern indicates a loss of hair density, suggesting a condition of hair thinning or alopecia.

Table summary: The table compares male and female patterns of hair loss, highlighting differences in their alternative names, the specific spatial patterns of hair recession, and the recommended concentrations of Minoxidil for treatment.

Chapter 4: Disorders of Glands

Types of Skin Glands

Comparison of Eccrine and Apocrine Glands

Image summary: This is an anatomical diagram. The figure illustrates the structure of human skin, detailing various glands and their pathways to the surface. It highlights the epidermis, dermis, and subcutaneous fat layers, showing the placement of eccrine glands, apocrine glands, and sebaceous glands, along with hair follicles and sweat pores. The diagram demonstrates that eccrine glands have a direct path to the surface via a dedicated duct, while apocrine glands and sebaceous glands are associated with the hair follicle. It can be inferred that the skin utilizes multiple specialized glandular systems to secrete substances, with some acting independently and others functioning in conjunction with hair growth.

• Three important glands: Eccrine sweat glands, Sebaceous glands, Apocrine sweat glands

• Eccrine glands lead to ducts open directly onto skin surface

• Sebaceous and Apocrine glands to require hair follicle to pour secretions

Modified and Ectopic Glands

Definition

Ectopic Sebaceous Glands: Sebaceous (oil) glands that are located in unusual places or open directly onto the skin surface without a hair follicle.

Ectopic Sebaceous Glands (open without hair follicles)

Table summary: The table lists various types of sebaceous glands, specifying their anatomical locations and characteristic physical appearances.

Image summary: This is a close-up photograph. The image shows a person's lips and the surrounding skin of the upper and lower face, focusing on the mouth area. There are visible small blisters and crusting on the upper lip, along with a small open sore. The condition suggests an active outbreak of a viral infection, such as herpes simplex, characterized by clustered vesicles and inflammation on the vermilion border of the lip.

Image summary: This is a clinical photograph. The image displays a close-up view of a breast nipple and areola, featuring a prominent, raised nodule on the nipple. The surrounding areolar skin appears textured with several smaller papules. The presence of a distinct mass on the nipple suggests an abnormal growth or lesion that requires medical evaluation to determine if it is benign or malignant.

Image summary: This is a clinical photograph. The image displays a close up view of skin on a genital area exhibiting multiple small, raised, flesh colored papules and irregular growths. The presence of these clustered, cauliflower like lesions suggests a viral infection, most likely consistent with genital warts caused by the human papillomavirus.

Table summary: This table lists various types of glands and their corresponding anatomical locations in the body.

Miliaria

• Obstruction of eccrine sweat ducts

Image summary: This is a clinical photograph. The image displays a close up view of human skin affected by a widespread eruption of small, raised bumps and red spots. The skin exhibits a dense distribution of papules and vesicles across the surface. The presence of numerous inflammatory lesions suggests an acute systemic reaction or an infectious skin condition characterized by extensive cutaneous involvement.

Table summary: The table compares different types of miliaria based on the depth of sweat duct obstruction and their corresponding clinical presentations, showing that as the level of obstruction moves from the superficial stratum corneum to the dermal-epidermal junction, the lesions transition from clear vesicles to red papules and finally to deep, flesh-colored papules.

Fox-Fordyce Disease

• Obstruction of apocrine sweat ducts

Image summary: This is a clinical photograph. The image displays a close up view of human skin showing a dense cluster of small, raised bumps known as papules. These lesions are concentrated in a specific area of the skin, appearing as a textured rash with varying degrees of elevation and distribution across the affected surface. The presence of these numerous small papules suggests a dermatological condition characterized by follicular or inflammatory skin eruptions.

Intensely itchy, skin-colored to reddish follicular papules

• Sites: apocrine-rich areas to axilla, areola, groin (Q)

Hidradenitis Suppurativa

Image summary: This is a clinical photograph. The image shows the axillary region of a person, displaying several raised nodules and open sores amidst hair-bearing skin. There is evidence of skin thickening and scarring in the affected area. The presence of recurrent nodules and draining sinuses in a skin-fold area suggests a chronic inflammatory condition such as hidradenitis suppurativa.

• Involvement of apocrine glands + secondary infection

• Presents with: painful nodular lesions, boil-like abscesses, sinuses, ulceration, scar formation

- Sites: apocrine gland-rich areas (axilla, groin)

Pyt Gold

Acne Vulgaris

• Disorder of the pilosebaceous unit

- 4 grades based on predominant lesion type

Table summary: The table outlines the characteristic lesions associated with grade one gland issues and the corresponding topical retinoid treatments used to manage them.

Table summary: The table outlines a progressive treatment strategy for acne based on severity grade, where the intensity of the medication increases from topical combinations for inflammatory papules to oral antibiotics for pustules, and finally to systemic isotretinoin for the most severe nodules and cysts.

Image summary: This is a clinical photograph. The image shows a close up view of human skin on the cheek and around the nose, displaying various types of acne lesions including open comedones and inflammatory papules. The presence of multiple blackheads and red bumps indicates a moderate case of acne vulgaris characterized by both non-inflammatory and inflammatory skin reactions.

Image summary: This is a clinical photograph. The image displays a close up view of human skin on the forehead, characterized by numerous small, flesh colored bumps and an uneven skin texture. The presence of these widespread papules suggests a dermatological condition such as acne or a similar skin disorder.

Image summary: This is a clinical photograph. The image shows a close up view of a person's lower face, specifically the cheek and jawline area, which is affected by numerous inflammatory skin lesions. The skin displays multiple red papules and pustules of varying sizes, indicating an active breakout of acne vulgaris.

Image summary: This figure is a clinical photograph. It displays a close up view of human skin affected by a dermatological condition, specifically identified by the text as Grade 3 Acne, characterized by numerous inflammatory papules and pustules across the skin surface. The presence of widespread redness and pus-filled lesions indicates a moderate to severe inflammatory response, suggesting a need for medical intervention to manage the breakouts and prevent scarring.

Image summary: This is a clinical photograph. The image displays a close-up view of a person's cheek and jawline, showing extensive skin inflammation characterized by numerous raised bumps, pustules, and areas of redness. The lesions are densely clustered across the mid-face and extend toward the chin. The presence of multiple inflammatory papules and pustules suggests a severe case of acne or a similar inflammatory dermatological condition.

Isotretinoin (13-cis Retinoic Acid)

Table summary: This table outlines the clinical properties and risks associated with 13-cis retinoic acid, highlighting its severe teratogenicity requiring a specific washout period, potential for liver toxicity, negative impacts on lipid levels, and the prevalence of lip dryness as a side effect.

Resistant Acne (Q)

• If acne not responding to isotretinoin leads to think hormonal cause leads to evaluate for hyperandrogenism (Q)

• Examiner clues: insulin resistance, hirsutism, irregular menstrual cycles, acanthosis nigricans, androgenetic alopecia

• If not treated with isotretinoin to lesions heal with very bad scarring to early treatment is crucial

Rosacea

• No comedones leads to key differentiating point from acne vulgaris

• Clinically: telangiectasias (dilated blood vessels) + erythema resembling malar rash

• Nasolabial folds: Involved in rosacea (vs S.L.E where nasolabial folds are Spared)

- Can also have papules and pustules (like acne but no comedones)

• Treatment: Topical metronidazole + Systemic doxycycline

Rosacea Triggers

• Sunlight, Alcohol, Smoking, Stress, Spicy food

Phyna (Tissue Irregularity)

Table summary: The table maps specific types of phyma to their corresponding anatomical locations on the face.

Image summary: This is a clinical photograph. The image shows a close up view of a person's face, specifically focusing on the nose and cheek area, which exhibits extensive redness and visible small blood vessels. The skin displays a pattern of telangiectasia, characterized by dilated capillaries appearing as fine, branching lines across the nasal bridge and the malar region.

High Yield

5 Definitions

Definition 1: Acne Vulgaris: A common skin condition that occurs when hair follicles become plugged with oil and dead skin cells.

Definition 2: Rosacea: A chronic inflammatory skin condition that causes redness and often small, red, pus-filled bumps on the face.

Definition 3: Comedones: Skin-colored, or brown, bumps that form as a result of clogged hair follicles; commonly known as blackheads or whiteheads.

Definition 4: Pilosebaceous unit: The structure in the skin that consists of a hair follicle and its associated sebaceous (oil) gland.

Definition 5: Telangiectasias: Small, dilated blood vessels visible on the surface of the skin.

Acne Vulgaris vs Rosacea Common: Both have papules, pustules, facial involvement Acne: Comedones Present | Pilosebaceous unit Rosacea: no comedones | Telangiectasias | Nasolabial folds Involved (vs S.L.E: spared) | Triggers: sun, alcohol, stress, spicy food Chapter 5: Disorders of Nails

Image summary: This is a clinical photograph. The image displays a close up view of a person's face, focusing on the nose which exhibits significant enlargement and a nodular, irregular surface texture. There is also noticeable redness across the nasal area and cheeks. The appearance indicates a severe case of skin thickening and tissue overgrowth on the nose, suggesting a chronic inflammatory or systemic condition.

Leukonychia (White Lines on Nails)

Table summary: The table distinguishes between true and apparent leukonychia based on the anatomical location of the problem, noting that true leukonychia originates in the nail matrix while apparent leukonychia originates in the nail bed.

Image summary: This is a clinical photograph. The image shows a close up view of several fingernails on a human hand. The nails exhibit a distinct pale or white appearance across the nail beds, with a narrow band of pink remaining at the distal edges.

Apparent Leukonychia Types

Table summary: The table outlines various nail conditions, associating specific visual appearances with their underlying medical causes, specifically highlighting different types of nail discoloration linked to renal and liver dysfunction.

Image summary: This is a clinical photograph. The image displays a close up view of a human fingernail featuring alternating light and dark transverse bands across the nail plate. The presence of these repeated horizontal stripes suggests a periodic disruption in the nail matrix, indicating a history of systemic illness or nutritional deficiencies that affected nail growth over time.

Image summary: This is a clinical photograph. The image displays the fingernails of several fingers, showing distinct discoloration and structural changes in the nail plates. The nails exhibit a characteristic half-and-half appearance, where the proximal portion is pale or white and the distal portion remains pinkish. This pattern suggests a systemic health condition affecting the nail bed and vascularity, often associated with chronic nutritional deficiencies or renal issues.

Image summary: This figure is a medical photograph. It displays a close up view of human fingernails with annotations identifying a condition known as Terry's Nails, which is associated with liver disorders. The annotations highlight a distinct pattern where the majority of the nail bed appears pale, while a narrow strip at the distal edge remains pink. Based on the visual evidence and labels, it can be inferred that this specific nail discoloration pattern serves as a clinical sign for diagnosing systemic health issues, particularly those affecting the liver.

Onychomycosis fungal Nail infection

• Dermatophytes to called tinea unguium

- Non-dermatophytes and candida to called

Onychomycosis (not tinea unguium)

Definition

Onychomycosis: A fungal infection of the nail.

Types of Onychomycosis

Table summary: This table lists the various types of onychomycosis and their full names, identifying one specific type as the most frequent occurrence.

Image summary: This is a clinical photograph. The image shows a close up view of a human toe with a nail that exhibits abnormal thickening and discoloration on one side. The nail plate appears distorted with a rough, crumbly texture along the lateral edge, while the rest of the nail remains relatively smooth. These findings are indicative of a nail infection or dystrophy, suggesting a localized pathological process affecting the nail matrix or bed.

Image summary: This is a clinical photograph. The image displays a close up view of a human fingernail exhibiting significant structural damage and discoloration. A substantial portion of the nail plate is thickened, crumbly, and detached from the nail bed, while the remaining section appears thinner and translucent. The condition suggests a severe nail infection or dystrophy, characterized by extensive nail plate degradation and abnormal growth.

Clinical Features

- Nail plate: yellow discoloration

• Subungual hyperkeratotic material below the nail plate

• Tunnels present in the nail

High Yield

Definition

Subungual hyperkeratosis: Thickening of the skin beneath the nail, often a sign of fungal nail infection or psoriasis.

Onychomycosis vs Nail Psoriasis Common features: thick yellow nails + subungual hyperkeratosis Psoriasis: nail pitting Present Onychomycosis: nail pitting Absent

Treatment

• Oral antifungals (systemic)

• Topical nail lacquers to remember with C.E.A.T (Q)

Mnemonic

Nail Lacquers: C.E.A.T (like C.E.A.T tyres)

- C = Ciclopiroxolamine

- E = Efinaconazole

- A = Amorolfine (Q) (morpholine group)

- T = Tavaborole

Paronychia (Infection of Nail Folds)

• Paronychia = infection of the nail folds

Table summary: This table compares acute and chronic paronychia, highlighting that the acute form is caused by bacteria and presents with rapid onset and severe pain, whereas the chronic form is associated with fungal infections and irritants, presenting with boggy swelling.

Table summary: The table compares the key signs and treatment approaches for two different conditions, contrasting the potential for lymphatic spread and the need for antibiotics or drainage in one case against the loss of cuticle and the use of topical antifungals and steroids in the other.

Image summary: This is a clinical photograph. The image displays a close up view of a human finger and nail, showing inflammation and skin discoloration around the nail fold, particularly on one side. The skin appears swollen and irritated, with a visible lesion and crusting near the base of the nail. These findings indicate a localized infection or inflammatory condition of the periungual tissue, suggesting a diagnosis such as paronychia.

Image summary: This is a clinical photograph. The image shows a human forearm and hand with a linear red streak extending from the upper arm down toward the wrist. The streak is most prominent along the inner side of the forearm and terminates near the wrist joint, where there is a localized area of swelling and redness. The appearance is consistent with lymphangitis, suggesting an inflammatory response or infection spreading through the lymphatic vessels from a distal site of entry toward the proximal lymph nodes.

Image summary: This is a clinical photograph. The image displays the fingernails of two fingers, showing significant discoloration and structural changes to the nail plates. The nails exhibit brownish pigmentation and an uneven surface texture, with the surrounding skin appearing swollen and inflamed. The presence of these nail changes suggests a systemic or localized pathological condition affecting the nail matrix or bed, indicating a diseased state compared to healthy nails.

Chapter 6: Pigmentary Disorders

Hyperpigmentation Disorders

• Melasma, Chikungunya to bigger macules and patches

• Freckles, Lentigines leads to small macular hyperpigmented lesions

Melasma (Chloasma) (Q)

Image summary: This figure consists of side-by-side clinical photographs. The images display the facial skin of a patient affected by melasma, showing hyperpigmented patches on the cheeks. The comparison indicates that the skin discoloration remains prominent across both views, suggesting a persistent condition of uneven skin tone.

Table summary: The table distinguishes between the epidermal and dermal variants of the condition based on color and Wood's lamp reaction, while describing the typical symmetrical presentation on the cheeks.

Table summary: The table outlines the occurrence of chloasma during pregnancy, identifying hormonal factors and medication as associated causes, and recommends a combination of chemical and physical sunscreens for management to prevent ultraviolet damage.

Image summary: This is a clinical photograph. The image shows a close up view of a person's face, specifically focusing on the mid-face area including the nose and upper lip. There is a noticeable growth or swelling on the right side of the nose, causing a distortion of the nasal structure and asymmetry of the nostrils. The skin in the affected area appears thickened. The presence of a localized mass on the nasal ala suggests a benign or malignant growth, leading to a structural deformity of the nose.

• Patient with severe joint pain, fever, retroorbital pain

• History of N.S.A.I.D intake to followed by pigmentation

• Melasma-like pigmentation over the nose to "Chik sign" (Q)

Freckles Sites: sun-exposed areas only

Image summary: This is a portrait photograph. The image shows a close up view of a woman's face and shoulders, featuring her facial features, hair, and jewelry. The subject has a neutral expression, looking directly at the camera with subtle makeup and visible freckles. The image captures a professional headshot of an individual.

• Melanocytes: number normal, activity increased

• Summer worsening / worsening present

• Association: Xeroderma pigmentosum (autosomal recessive)

Lentigines

• Melanocyte Number increased (unlike freckles where only activity increases)

• Both sun-exposed and sun-protected sites

• No summer worsening

• Association: Peutz-Jeghers syndrome arrow mucosal lentigines plus hamartomatous polyps in gastrointestinal system

Image summary: This figure consists of two clinical photographs. The images display skin manifestations, specifically focusing on the lower lip and a broad area of the torso. The photographs show widespread hyperpigmented macules and patches on the lip and skin, indicating a systemic condition characterized by increased pigmentation. It can be inferred that the patient is experiencing diffuse cutaneous hyperpigmentation affecting multiple anatomical sites.

Table summary: The table distinguishes between freckles and lentigines by contrasting their underlying mechanisms, distribution, seasonal behavior, and associated syndromes, noting that freckles involve increased melanocyte activity in sun-exposed areas that worsen in summer, whereas lentigines involve an increased number of melanocytes in both sun-exposed and protected areas without seasonal changes.

Nevi (Birthmarks)

Table summary: The table compares Congenital Melanocytic Nevus and Becker's Nevus, highlighting that the former appears at birth with darker coloration and thickened skin, while the latter emerges during puberty with lighter coloration and normal skin texture. Both conditions exhibit hair growth, but Congenital Melanocytic Nevus can be bilateral, whereas Becker's Nevus is strictly unilateral.

Image summary: This is a clinical photograph. The image displays the back and shoulder of an individual featuring a large, dark, pigmented skin lesion that covers a significant portion of the upper back and extends down the arm. The lesion is characterized by dense, coarse hair growth and a textured, thickened skin surface. The presence of extensive hyperpigmentation and hypertrichosis across a wide anatomical area suggests a congenital melanocytic nevus with associated hair growth.

Image summary: This figure is a clinical photograph. It shows a close up view of a person's shoulder and upper back area, highlighting a dense growth of coarse hair. The image demonstrates a significant concentration of hair in a specific region of the skin, indicating an area of hypertrichosis or localized excessive hair growth.

Dermal Melanocytosis

• Problem during melanocyte migration from neural crest cell to stratum basale to melanocyte stuck in

deeper layers leads to bluish-gray pigmentation

Table summary: The table compares different types of blue nevi, distinguishing them by their typical anatomical locations and their long-term persistence, noting that while Mongolian spots are temporary, Nevus of Ota and Nevus of Ito are lifelong conditions.

Image summary: This figure consists of two side-by-side clinical photographs. The images display skin lesions on different parts of the body, with the left image showing a large, dark, diffuse patch on the lower back and buttocks of an infant, and the right image showing a textured, lighter-colored plaque on the upper back of an individual. The comparison suggests different presentations of cutaneous vascular or pigmentary anomalies, where one presents as a deep, uniform discoloration and the other as a more superficial, irregular, and textured lesion.

Image summary: This is a clinical photograph. The image shows a close up view of a human eye and the surrounding skin, highlighting areas of pigment loss on the eyelid and the adjacent facial skin. The presence of these depigmented patches indicates a loss of melanin, which is characteristic of vitiligo affecting the periocular region.

2 Definitions

Definition 1: Nevus of Ota: A birthmark characterized by bluish-grey pigmentation on the face, commonly affecting the eye and surrounding skin.

Definition 2: N.d:Y.A.G laser: A type of laser that emits light at a wavelength of 1064 nanometers, often used for treating pigmented lesions and blood vessels in the skin.

Treatment of Nevus of Ota and Ito: N.d:Y.A.G laser

Nevus Anemicus vs Nevus Depigmentosus

• Both present from birth implies hypopigmented skin lesion

Table summary: The table compares Nevus Anemicus and Nevus Depigmentosus across pathology, Wood's lamp findings, and diascopy results, highlighting that the former is a vascular disorder while the latter is a pigmentary defect.

Image summary: This figure consists of two side-by-side clinical photographs. The images show a diagnostic procedure where a transparent slide is placed over skin lesions on the face of two different individuals to examine pigment loss. The comparison indicates that while one patient exhibits subtle, diffuse changes in skin tone, the other shows distinct, well-defined depigmented patches, suggesting different presentations or stages of vitiligo.

Piebaldism (Congenital Depigmentation)

Image summary: This is a clinical photograph. The image displays a young child with extensive areas of skin depigmentation interspersed with darker, pigmented spots across the torso, legs, and scalp. The distribution shows a mixture of large white patches and smaller dark macules. The presence of these contrasting skin tones suggests a condition characterized by the loss of pigment in some areas and the retention or recurrence of pigment in others, which is characteristic of certain types of vitiligo.

Image summary: This is a photograph. The image depicts a woman holding a young child, with both individuals exhibiting patches of depigmentation on their skin and hair. The woman has a prominent white patch of hair and skin on her forehead and scalp, while the child shows similar depigmentation on the face. The visual evidence suggests a familial occurrence of vitiligo, indicating a genetic predisposition to the condition where the skin loses its pigment.

Image summary: This figure is a clinical photograph. It shows an infant with a distinct patch of depigmented hair on the forehead and scalp, contrasting with the darker hair on the sides of the head. The presence of a localized white forelock indicates a loss of pigment in that specific area, which is a characteristic manifestation of conditions such as piebaldism or segmental vitiligo.

Table summary: The table describes the pathology of a specific type of vitiligo, attributing it to a congenital issue involving the migration of neural crest cells.

Table summary: This table outlines the genetic inheritance, typical clinical presentation, and associated syndromes for a specific type of vitiligo, highlighting its link to KIT gene mutations and its overlap with Waardenburg syndrome.

Vitiligo (Acquired Autoimmune Depigmentation)

Pyt Gold

• Acquired autoimmune leads to destruction of melanocytes

Clinical: milky white / chalky white depigmented patches

• Wood's lamp: accentuation of milky white color

Image summary: This is a clinical photograph. The image shows a person's chin and neck area featuring several irregular patches of skin that have lost their natural pigment, appearing much lighter than the surrounding skin. These depigmented areas vary in size and shape, with some showing a speckled pattern of remaining pigment. The presence of these distinct, pale patches on the skin is indicative of vitiligo, a condition characterized by the loss of melanocytes.

Table summary: This table outlines the different types of vitiligo and their distinguishing characteristics. It contrasts segmental vitiligo, which is unilateral, appears in early childhood, and follows dermatomes, with other forms such as focal, acrofacial, vulgaris, and universalis. Among these, vulgaris is identified as the most frequent variety, while universalis is characterized by widespread depigmentation with minimal spared skin.

Image summary: This figure is a series of anatomical diagrams. It illustrates various patterns of vitiligo across five human figures, labeled as focal, segmental, acrofacial, generalized, and universal. The diagrams show a progression of skin pigment loss, ranging from small isolated patches in the focal type to widespread depigmentation in the universal type. It can be inferred that vitiligo manifests in diverse distributions, varying from localized areas to nearly total body involvement, with some types affecting specific segments or extremities and others appearing symmetrically or randomly across the body.

Image summary: This is a clinical photograph. The image shows a person with extensive depigmented patches of skin across the face, neck, chest, hands, and abdomen. The distribution of the skin discoloration is widespread and asymmetrical, characterized by a stark contrast between the natural skin tone and the white patches.

Image summary: This is a clinical photograph. The image displays a person with patches of depigmentation affecting the skin of the face, specifically around the mouth, as well as extensive areas on both hands and fingers. The distribution of these light-colored patches indicates a loss of pigment in various skin regions, which is characteristic of vitiligo.

Poor Prognostic Markers for Repigmentation

• Long-standing vitiligo

• Over bony prominences

• Leukotrichia (hair becoming white)

• Lip-tip involvement (lips and tip of penis)

Treatment

• Limited disease: topical steroids or tacrolimus

More than 20% body surface area: phototherapy (narrow band ultraviolet B)

Contact Leukoderma

• Rubber footwear to monobenzyl ether of hydroquinone to destroys melanocytes to contact leukoderma

• Bindid arrow paratertiary butyl phenol P.T.B.P (Q) arrow destroys melanocytes arrow depigmentation at bindi site

Image summary: This is a clinical photograph. The image displays the dorsal surfaces of two feet, showing multiple irregular patches of depigmented skin contrasting with the surrounding natural skin tone. The presence of these starkly white, colorless areas across both feet indicates a loss of melanin, which is characteristic of a depigmenting skin condition.

Image summary: This figure consists of a pair of clinical photographs. The images show a close up view of a person's forehead, focusing on a specific skin lesion located centrally above the eyebrows. Comparing the two images, the lesion appears lighter and more faded in the first photograph, while it appears darker and more pronounced in the second photograph. The difference in appearance suggests a change in the lesion's state or the application of a diagnostic agent, indicating a progression or a specific reaction associated with the skin condition.

Chapter 7: papulosquamous Disorders

Pyt Gold

Psoriasis

• Site: extensor surfaces to silvery white scaling (Q)

• Genetic association: H.L.A-C.W.6 and H.L.A-B.27

• Associated with metabolic syndrome, joint involvement, H.I.V (severe form)

Mnemonic

Drugs worsening psoriasis: P.L.A.B's P = Painkillers | L = Lithium | A = Antimalarials | B = Beta blockers | S = Steroid withdrawal

+ Alcohol and Smoking

Image summary: This is a clinical photograph. The image displays the lower limbs of a patient exhibiting extensive skin lesions characterized by thick, scaly plaques and redness. The presence of these widespread, well-defined inflammatory patches suggests a severe manifestation of psoriasis affecting the legs.

Table summary: This table outlines different types of psoriasis, distinguishing between Plaque and Guttate varieties based on their characteristic clinical features and respective treatment approaches.

Table summary: This table outlines different types of psoriasis, noting that flexural psoriasis is characterized by a lack of scaling, while pustular and erythrodermic forms can be triggered by steroid withdrawal. It also specifies the preferred treatments for these conditions, highlighting acitretin for the pustular type and systemic therapy for the erythrodermic type.

Image summary: This figure consists of two clinical photographs. The images display different presentations of skin conditions on the human body, specifically showing a widespread distribution of small red spots across the back in one panel and concentrated red inflammation within the skin folds of the chest in the other. These visuals indicate that psoriasis can manifest in diverse forms, ranging from disseminated guttate lesions to localized inverse patterns.

Image summary: This is a clinical photograph. The image displays a section of human skin affected by a dermatological condition, characterized by red patches and the presence of numerous small, white, raised bumps or pustules distributed across the inflamed areas. The presence of these pustules on an erythematous base indicates a pustular form of psoriasis, suggesting an inflammatory skin response characterized by sterile pustule formation.

Psoriatic Arthritis (Q)

Image summary: This is a clinical photograph. The image displays a section of skin characterized by widespread redness and the presence of thick, flaky scales. The skin appears inflamed with irregular patches of peeling and scaling. The appearance is consistent with a dermatological condition, specifically showing the characteristic plaque formation and skin shedding associated with psoriasis.

Most commonly involved joint: distal interphalangeal joint (Q)

• X-ray: pencil-in-cup deformity

Image summary: This is a clinical photograph. The image displays a close up view of several fingers and their corresponding nail beds. The nails exhibit characteristic changes including thickening, surface irregularities, and a separation of the nail plate from the bed, which are indicative of nail psoriasis.

Dactylitis (inflammation of the digit)

Important Signs in Psoriasis

Table summary: The table describes various clinical signs and phenomena associated with psoriasis and other skin conditions, distinguishing between autoimmune responses and auto-inoculation while explaining the physiological causes of specific skin reactions.

Image summary: This figure is a clinical photograph. It displays a skin lesion characterized by a central eroded area surrounded by an inflamed border with peeling skin. The image indicates a localized adverse reaction to treatment, manifesting as a skin ulceration or severe dermatitis.

Mnemonic

Image summary: This is a clinical photograph. The image displays several fingers showing significant nail deterioration, characterized by thickening, discoloration, and crumbling of the nail plates, along with inflammation of the surrounding skin. The condition indicates severe nail dystrophy and periungual inflammation, suggesting a strong adverse reaction to a treatment or a systemic pathology affecting the nail matrix and bed.

Image summary: This is a clinical photograph. The image displays a section of skin affected by several raised, scaly, and inflamed patches of varying sizes. These lesions appear as irregular plaques with a textured surface, indicating a dermatological reaction. The presence of these skin abnormalities suggests an adverse reaction to a medical treatment, manifesting as an inflammatory skin condition.

- P = Pitting (irregular, deep, coarse) (Q)

- O = Oil drop sign (pathognomonic, yellow/salmon) (Q),

- Onycholysis

- L = Leukonychia

- I = Irregular pitting pattern

- S = Splinter hemorrhage

- H = Hyperkeratosis (subungual)

Image summary: This is a clinical photograph. The image displays a human fingernail exhibiting multiple small, white, pinpoint spots distributed across the nail plate, with arrows pointing to specific lesions. The presence of these white spots indicates leukonychia, which in this context represents an adverse effect of medical treatment.

Image summary: This is a clinical photograph. The image displays a close up view of a human fingernail exhibiting significant discoloration, thickening, and surface irregularities. The nail plate shows areas of yellowing and structural degradation, particularly along the edges and distal portion. These observations indicate a pathological condition of the nail, suggesting an adverse reaction to treatment or an underlying nail disorder characterized by dystrophy and discoloration.

Treatment of Psoriasis

Table summary: The table outlines the recommended treatment strategies for various psoriasis conditions based on the severity of body surface area involvement and specific clinical presentations. It distinguishes between topical therapies for limited areas and phototherapy or systemic medications for more extensive cases, while specifying preferred drug choices for pustular psoriasis and psoriatic arthritis, and identifying safe alternatives for patients during pregnancy.

Table summary: The table outlines the distinct adverse effects associated with different drug treatments, noting that PUVA is linked to an elevated risk of skin cancer, while Cyclosporine is associated with kidney toxicity and high blood pressure.

Table summary: This table outlines the adverse effects associated with specific medical treatments, highlighting the toxic and teratogenic risks of Methotrexate and Acitretin, while also introducing newer therapeutic options.

Mnemonic

Lichen Planus

The P's of Lichen Planus Purple, Polygonal, Plane-topped, Pruritic Papules/Plaques Heal with Pigmentation | Flexors | Pterygium (nails) | Pup tenting sign

• Autoimmune disorder to many P's

• Location: flexors (Q)

Image summary: This is a clinical photograph. The image shows the skin of two limbs, likely the knees or elbows, exhibiting widespread inflammatory skin lesions. These lesions appear as raised, bumpy papules and thickened patches of skin. The distribution of the rash is bilateral and symmetrical, suggesting a systemic reaction or a localized adverse effect of a treatment affecting both sides of the body.

Triggers for Lichen Planus

• Amalgam (mercury dental filling)

• Hepatitis C infection (important association)

Drugs: Chloroquine, Hydroxychloroquine, Beta blockers, A.C.E inhibitors

Histopathology (Q)

• Wedge-shaped hypergranulosis (thickening of stratum granulosum)

• Band-like lymphocytic infiltrate, Basal cell degeneration, Max-Joseph spaces, Civatte bodies

• not: Munro microabscess (Q) (that is psoriasis)

Treatment

• Limited: topical steroids (Q)

• Generalized: oral steroids

Wickham's Striae

• Lacy reticular network pattern to seen on skin and mucosa

• Cannot be wiped off

Image summary: This is a clinical photograph. The image displays a circular skin lesion on a person's skin, featuring a pale, textured center with a network of fine lines identified as Wickham striae. The presence of these characteristic lace-like patterns within the lesion is indicative of lichen planus, a chronic inflammatory condition affecting the skin and mucous membranes.

Image summary: This figure is a clinical photograph. It displays a close up view of oral mucosa adjacent to teeth, showing areas of white patches and redness on the soft tissue. The presence of these white plaques and erythematous regions suggests an inflammatory response or a tissue reaction, which is consistent with the adverse effects of medical treatments in the oral cavity.

Nail Changes in Lichen Planus

- Dorsal pterygium (Q): proximal nail fold destroys nail plate to attaches to nail bed

• Thinning of nail plate to most common nail finding in lichen planus

Pityriasis Rosea

• Initial lesion: herald patch / mother patch (Q) arrow annular lesion with collarette scale

• Later: similar lesions develop along Langer's lines, leading to a Christmas tree pattern (Q)

• Scale: cigarette paper-like scale

• Association: H.H.V-6 and H.H.V-7 (7 is important)

• Management: Conservative (self-limiting)

Image summary: This figure consists of two clinical photographs. The left image provides a close-up view of a skin lesion characterized by an elevated, scaly, and erythematous plaque. The right image shows a wide view of a person's back, displaying a widespread distribution of similar reddish papules and plaques concentrated primarily along the midline and upper back. The presence of these extensive, inflammatory skin lesions across a large surface area suggests a systemic or widespread dermatological condition.

Pityriasis Rubra Pilaris

• Reddish-orange papules to perifollicular involvement (pilaris)

• Islands of sparing (very characteristic)

• Palmoplantar keratoderma (thickening of palms/soles)

- Histology: checkerboard pattern (Q) leads to alternating bands of orthokeratosis and parakeratosis

Image summary: This is a clinical photograph. The image shows the soles of two feet exhibiting widespread redness and significant skin thickening. The skin appears shiny and tight with visible scaling and fissuring across the plantar surfaces, extending to the toes. The presentation indicates a severe dermatological condition characterized by hyperkeratosis and inflammation, consistent with a systemic skin disorder.

Lichen Nitidus

Image summary: This figure is a histological micrograph. It displays a cross-section of skin tissue, focusing on the epidermal layer and the overlying stratum corneum. The image shows a characteristic thickening of the outer skin layer with an irregular, fragmented surface. The observation of hyperkeratosis and the specific pattern of scaling suggest a pathological skin condition, indicating an abnormal accumulation of keratin proteins on the skin surface.

• Micropapules over dorsum of hands and genitals (Q)

- Usually seen in children

- Histology: claw clutching ball appearance

Image summary: This figure consists of a clinical photograph and a corresponding histological slide. The left side displays a physical examination of a patient's genital area showing small, flesh-colored papules, while the right side shows a microscopic cross-section of skin tissue featuring a well-defined epidermal proliferation. The combination of the clinical presentation and the histological findings indicates a benign growth characterized by specific cellular arrangements within the skin layers.

Table summary: This table associates specific visual characteristics of skin scales with their corresponding dermatological diseases, linking distinct appearances such as silvery white, yellow greasy, powdery, collarette, and fish-like textures to specific conditions.

Table summary: This table categorizes specific types of skin scales and associates them with their corresponding dermatological conditions, linking leaf-like or cornflake-like appearances to Pemphigus foliaceus and mica-like scales to Pityriasis lichenoides chronica.

Chapter 8: Eczema & Histamine-Related Disorders

Types of Eczema

Table summary: The table compares different stages of eczema, illustrating a progression from acute to chronic forms. It highlights how clinical features evolve from inflammatory oozing and crusting in the acute phase to redness and scaling in the subacute phase, and finally to skin thickening and hyperpigmentation in the chronic phase, with corresponding histopathological changes such as spongiosis and acanthosis.

Image summary: This is a clinical photograph. The image displays a skin lesion on a limb characterized by thickened skin with a rough, scaly texture and irregular pigmentation. The appearance is consistent with contact dermatitis, showing significant inflammation and skin surface changes.

Image summary: This figure is a photomicrograph of a tissue sample. It displays a histological section of skin characterized by a thickened epidermal layer with elongated downward projections extending into the underlying dermis. The image illustrates the structural changes associated with contact dermatitis, specifically showing epidermal hyperplasia and the formation of prominent rete ridges.

Table summary: This table compares irritant contact dermatitis and allergic contact dermatitis across several clinical dimensions. Irritant contact dermatitis is characterized as the more frequent form, resulting from direct physical or chemical damage and remaining strictly localized to the point of contact. In contrast, allergic contact dermatitis involves a delayed hypersensitivity immune response, requires prior sensitization, and can spread beyond the initial contact site. The two conditions differ in their common triggers and diagnostic methods, with the former being diagnosed clinically and the latter requiring patch testing.

Important Allergens in Allergic Contact Dermatitis

Table summary: This table lists various common allergens and identifies their corresponding sources, highlighting a range of triggers including jewelry, construction materials, cosmetic products, and rubber.

• Allergens settle on exposed skin leads to dermatitis

• Important allergen: Parthenium (congress grass) (Q) to chemical: sesquiterpene lactone

- Sites: face + V-area of neck (exposed areas)

Image summary: This figure is a composite image consisting of two side-by-side photographs. The left photograph shows a close-up view of a man's face and upper chest exhibiting widespread skin nodules and thickening. The right photograph shows a plant with slender leaves and small clusters of flowers. The juxtaposition of these images suggests a clinical association between the skin condition observed in the patient and exposure to the depicted plant species.

P.Y.T gold

Atopic Dermatitis

• Endogenous eczema with environmental triggers (both exogenous + endogenous)

• Mechanism: Type 1 Hypersensitivity

• Diagnosis: Hanifin-Rajka criteria (clinical examination = investigation of choice)

• Itch-scratch cycle to more scratching to more itching

Age-Based Distribution (Q)

Table summary: The sites of involvement shift from the face and extensor surfaces in infancy to the face and flexural areas in childhood, eventually concentrating primarily in flexural areas during adulthood.

Distribution of Atopic Dermatitis A.D by Age

Seborrheic dermatitis overlap Hanifin-Rajka Criteria (Major — need 3 of 4)

Image summary: This figure is a medical illustration. It depicts the distribution of skin lesions across three different age groups: an infant, a child, and an adult. The illustration shows affected areas on the face, arms, and legs, with magnified views highlighting the texture of the skin eruptions on the adult. The content indicates that the condition affects individuals across various stages of life, with a tendency for lesions to appear on the extremities and facial regions regardless of age.

Image summary: This figure is a clinical photograph. It shows the face of an infant with extensive skin lesions, characterized by redness and crusting on the cheeks and around the nose, along with an inset image showing inflammation of the lips. The distribution and appearance of the lesions suggest a severe inflammatory skin condition or an infectious process affecting the facial region.

Table summary: The table outlines the key diagnostic criteria for atopic dermatitis, highlighting the essential role of pruritus, the chronic nature of the condition, a personal or family history of atopy, and characteristic morphological patterns and distribution.

Table summary: The table lists various clinical signs and their corresponding physical descriptions, focusing on dermatological and ocular manifestations.

Image summary: This figure consists of two clinical photographs. The first image shows a close up of a patient's face focusing on the area below the eyes, highlighting the presence of additional skin creases in the infraorbital region. The second image displays a section of skin with a cross-shaped mark, illustrating a skin reaction known as white dermographism. Together, these images demonstrate specific dermatological signs, suggesting a condition characterized by abnormal skin folding around the eyes and a hypereactive skin response to physical stimulation.

Image summary: This is a close-up photograph. The image displays a human eye, focusing on the iris and pupil, with the surrounding sclera and eyelashes visible. The pupil appears elongated and oval-shaped rather than circular, suggesting a medical condition such as corectopia or a structural abnormality of the eye.

Image summary: This is a medical photograph. The image shows a close up view of a human eye, focusing on the pupil and iris, where a cloudy, opaque lesion is visible over the center of the cornea. The presence of this dense opacity indicates a corneal ulcer or scar, which obstructs the clear path of light into the eye and likely results in significant visual impairment.

Other Important Eczemas

Seborrheic Dermatitis

- Sites: scalp, face, nasolabial folds, retro-auricular region

• Scales: greasy, yellow

- Driven by abnormal inflammatory response to Malassezia yeast

• Severe disease associations: Parkinson's disease, H.I.V infection

• In infants: "Cradle cap"

Image summary: This figure consists of two clinical photographs. The first image shows a close up of a person's lower face, specifically the area around the nose, upper lip, and chin, exhibiting crusting and scaling of the skin. The second image shows a person's scalp with extensive yellowish crusting and redness. The images demonstrate a widespread dermatological condition characterized by significant skin inflammation and the formation of thick crusts across different body sites.

Stasis Eczema (Gravitational / Varicose Eczema)

• Associated with chronic venous insufficiency

• C.E.A.P Classification: C.4.a = pigmentation/eczema; C.4.b = lipodermatosclerosis ("inverted champagne bottle" appearance)

Image summary: This is a clinical photograph. The image displays the lower legs and ankles of a patient, showing widespread skin discoloration and swelling. There is a noticeable difference in skin tone between the upper and lower portions of the shins, with the lower areas appearing more deeply pigmented and inflamed. The presence of bilateral edema and chronic skin changes suggests a systemic condition affecting circulation or fluid retention in the lower extremities.

Pityriasis Alba

• Scaling plus hypopigmentation (alba equals white) arrow child's face

• Associated with atopy

• Important differential: indeterminate leprosy (which does not have scaling)

Pompholyx (Dyshidrotic Eczema) (Q)

• Deep-seated vesicles (tapioca-like) on palms and soles leads to intensely itchy

Image summary: This is a clinical photograph. The image shows a close up view of a human palm featuring numerous small, fluid filled blisters and raised bumps across the skin surface. The presence of these widespread vesicles suggests an inflammatory skin condition or an allergic reaction affecting the palmar region.

Discoid (Nummular) Eczema

• Coin-shaped (nummular) eczematous lesions

• Differential: tinea arrow tinea has central clearing plus peripheral scaling; discoid eczema does not

Histamine-Mediated Disorders

Urticaria

• IgE-mediated Type 1 hypersensitivity leads to mast cell degranulation which leads to histamine release

Classic lesion: tran-zee-unt wheals (lasting less than 24 hours)

• Triple response of Lewis: Erythema (capillary dilation) leads to Flare (arteriolar dilation) leads to Wheal (edema exudation)

• Dermographism leads to exaggerated wheal response on stroking normal skin

Image summary: This figure consists of two clinical photographs. The images display skin reactions on different parts of the body, showing raised, reddish welts and inflammation. The left image shows an irregular area of swelling and redness on a limb, while the right image shows raised skin forming the word dermographism on a person's back. The evidence suggests a condition where the skin is hypersensitive to physical pressure, resulting in the formation of wheals in the exact pattern of the stimulus applied.

Cholinergic Urticaria

• Trigger: increase in core body temperature leads to sweating, exercise, hot showers

• Pinpoint small wheels

Image summary: This is a clinical photograph. The image shows a close-up view of human skin characterized by numerous small, raised bumps distributed across the surface. These papules appear densely packed and uniform in size, creating a textured appearance on the skin. The presence of these widespread eruptions suggests an inflammatory skin condition or an allergic reaction, indicating a systemic or localized cutaneous response.

Hereditary Angioedema

not histamine-related

• Bradykinin mediated

• Cl esterase inhibitor deficiency

• Sudden recurrent episodes of non-pitting edema

• Can involve subglottic area to airway blockage to life-threatening emergency

• No itching (because no histamine involvement)

Cutaneous Mastocytosis (Urticaria

Pigmentosa)

• Mast cell proliferation in skin arrow C-Kit mutations slash C.D.117

• Multiple hyperpigmented macular lesions over trunk to usually in children

• When involved skin is stroked to wheal response to Darier sign

High Yield

Image summary: This is a clinical photograph. The image displays a person's skin with numerous scattered, dark, circular lesions and one larger, inflamed area of redness. The presence of widespread maculopapular lesions suggests a systemic skin condition or an inflammatory response.

Dermographism vs Darier Sign Dermographism: wheal on Normal skin Darier sign: wheal on Lesional skin (involved/hyperpigmented skin in mastocytosis)

• Mast cell staining: toluidine blue

Chapter 9: Genodermatoses / Phacomatoses

Neurofibromatosis Type 1 N.F-1

• Autosomal dominant (Q) to presenting from early childhood

Table summary: The table outlines the diagnostic clinical features and specific quantitative or qualitative criteria required for the identification of neurofibromatosis, detailing skin manifestations, ocular findings, and nerve tumors.

Image summary: This figure consists of two clinical photographs. The images display skin lesions on different parts of a person's body, with one image showing the cheek area next to a coin for scale and the other showing the axillary region. The photographs reveal multiple light brown, oval-shaped macules of varying sizes distributed across the skin. These findings are characteristic of cafe-au-lait spots, which are often associated with genetic conditions such as neurofibromatosis.

Image summary: This figure is a clinical photograph. It shows a close up view of human skin affected by numerous cutaneous growths. The skin is covered in a high density of nodules that vary in size, ranging from small papules to larger, protruding masses. The distribution of these growths is widespread across the visible area of the limb. The presence of multiple, varying sized nodules suggests a systemic condition characterized by the proliferation of benign or malignant tumors, typical of neurofibromatosis.

Image summary: This is a clinical photograph. The image shows a person with a massive, irregular growth extending from the left side of the face and head, significantly distorting the facial features and covering a large portion of the cheek and jaw area. The growth appears lobulated and dense, indicating a severe pathological condition such as a large tumor or congenital malformation.

Image summary: This figure consists of clinical photographs. The images display several raised, fluid-filled blisters on a patch of inflamed skin, with one image showing a finger applying pressure to a lesion. The presence of these tense vesicles on an erythematous base suggests an acute inflammatory or infectious skin condition characterized by blistering.

Image summary: This is a medical photograph. The image shows a close-up view of a human eye, focusing on the iris and pupil, where multiple small, brownish nodules are distributed across the iris surface. The presence of these numerous pigmented deposits suggests a systemic or ocular condition characterized by the accumulation of abnormal deposits within the iris tissue.

Tuberous Sclerosis Complex

• Autosomal dominant leads to presenting from early childhood

Also called Epiloia = Epilepsy (most important C.N.S manifestation) + Low I.Q + Adenoma sebaceum

Table summary: The table lists the characteristic clinical features and diagnostic manifestations associated with a specific condition, detailing various skin lesions such as facial rashes, hypopigmented patches, and fibromas, alongside neurological impacts like epilepsy and cognitive impairment.

Table summary: The table provides a mnemonic to categorize the various cutaneous and systemic clinical manifestations associated with Tuberous Sclerosis, linking specific skin lesions and internal organ tumors to a memory aid.

Image summary: This figure consists of two side-by-side clinical photographs. The left image shows a close-up of a person's face featuring numerous small, raised nodules and larger papules concentrated around the nose, cheeks, and chin. The right image shows a section of skin with patches of depigmentation and lighter skin tones compared to the surrounding area. The contrast between the two images highlights distinct dermatological conditions, where one presents as hypertrophic skin growths and the other as a loss of skin pigment.

Image summary: This figure consists of two clinical photographs. The first image displays a close up of skin on a body part showing thickened, folded, and irregular skin textures. The second image shows several fingers with abnormal nail growth and discoloration. The visual evidence suggests a systemic dermatological condition characterized by significant skin hyperkeratosis and nail dystrophy, which is consistent with a diagnosis of ichthyosis.

Table summary: This table compares three types of ichthyosis based on their prevalence, genetic inheritance, molecular defects, and clinical presentation. Ichthyosis Vulgaris is the most frequent form, characterized by an autosomal dominant inheritance and fine scales primarily on the lower limbs. X-Linked Ichthyosis is less common, featuring recessive inheritance and darker scales concentrated on the trunk. Lamellar Ichthyosis is the rarest form, appearing at birth as a collodion baby with generalized plate-like scales and distinct facial abnormalities.

Image summary: This figure consists of two side-by-side clinical photographs. The images display the skin texture of individuals affected by ichthyosis, showing varying degrees of skin scaling and dryness. The left image shows fine, light scaling across the skin surface, while the right image shows more pronounced, deep, and geometric scale patterns. It can be inferred that ichthyosis manifests in different severities, ranging from mild dryness to severe, thick, plate-like scaling of the epidermis.

Image summary: This figure is a composite of clinical photographs. The images display a newborn infant with widespread skin abnormalities, showing severe redness and scaling across the face, torso, and extremities. The infant exhibits significant inflammation of the lips and eyelids, alongside thick, peeling skin on the body and genital area. The visual evidence indicates a systemic dermatological condition characterized by extreme skin dryness and shedding, consistent with a diagnosis of ichthyosis.

Chapter 10: Bacterial Infections

Hair Follicle Infections

Table summary: The table distinguishes between three types of follicular infections based on the extent of the affected area and the resulting clinical presentation, showing a progression from single follicle involvement to larger clusters of nodules.

Impetigo

Table summary: This table compares non-bullous and bullous impetigo, noting that non-bullous impetigo is more frequent, often occurs on the face, and is caused by multiple organisms. In contrast, bullous impetigo is less common, caused exclusively by Staphylococcus aureus, and involves a toxin-mediated mechanism that results in flaccid bullae.

Image summary: This is a clinical photograph. The image shows a close up view of human lips exhibiting significant inflammation, swelling, and the presence of honey-colored crusting and scaling across the vermilion border and adjacent skin. The skin appears irritated and thickened in the affected areas. The presence of these crusts and the localized inflammation suggest a dermatological condition characterized by epidermal scaling and potential secondary infection.

Image summary: This is a clinical photograph. The image displays the lower face and lips of an individual, showing significant skin abnormalities including thick, scaly patches and honey-colored crusting around the mouth and nose. The lips appear swollen and inflamed. These clinical signs suggest a severe dermatological condition characterized by extreme skin dryness and secondary bacterial infection.

Staphylococcal Scalded Skin Syndrome Ritter Disease

• Extension of bullous impetigo leads to exfoliative toxin spreads systemically

• Affects infants to entire skin peeling

• Desmoglein-1 not present in mucosa to oral mucosa is Spared

• Nikolsky's sign: Positive

Image summary: This is a clinical photograph. The image displays the back and upper limbs of a child exhibiting extensive skin peeling and redness across a large portion of the body surface. The skin appears to be shedding in large sheets, leaving behind raw and inflamed areas. The widespread nature of the skin detachment and the underlying inflammation suggest a severe dermatological condition characterized by a compromised skin barrier and significant epidermal loss.

Reactive Arthritis (Reiter Disease)

• Triggers: Campylobacter, Shigella, Chlamydia infections

• Triad: Conjunctivitis + Urethritis + Arthritis ("Can't see, can't pee, can't climb a tree")

• Skin changes: Keratoderma blennorrhagicum (soles) + Circinate balanitis (genitalia)

Image summary: This figure consists of two clinical photographs. The images display dermatological conditions affecting the soles of the feet and the glans penis, showing varying degrees of skin thickening, scaling, and reddish papules. The presence of widespread hyperkeratotic plaques on the feet and distinct lesions on the genital area suggests a systemic skin disorder characterized by abnormal skin cell proliferation.

Mnemonic Reactive Arthritis: a-cubic

- A = Arthritis | C = Conjunctivitis | U = Urethritis

- B = Blennorrhagicum (keratoderma) | I = Infections

- (trigger) | C = Circinate (balanitis)

Ecthyma pyogenicum (deeper variant of impetigo): Staphylococcus

Erysipelas vs Cellulitis

Table summary: This table compares erysipelas and cellulitis, highlighting that erysipelas is caused by a specific streptococcus species and affects shallower skin layers with well-defined margins, whereas cellulitis involves a broader range of organisms and penetrates deeper into the subcutaneous tissue with ill-defined margins. A key clinical distinction is the presence of Milian's ear sign in erysipelas due to its ability to infect areas lacking subcutaneous tissue, which is not possible for cellulitis.

Image summary: This figure consists of two clinical photographs. The images display skin lesions on different parts of the body, specifically showing inflammation and swelling on the cheek and ear area in one view, and a similar inflammatory nodule on the elbow in the other. The presence of these lesions across multiple joint and facial areas suggests a systemic inflammatory condition characterized by subcutaneous nodules and cutaneous involvement.

Erythrasma and Pitted Keratolysis

Table summary: This table compares Erythrasma and Pitted Keratolysis across their causative organisms, clinical presentations, and diagnostic investigations, highlighting that the former presents as hyperpigmented patches in skin folds and is identified by coral red fluorescence, while the latter manifests as small pits on the soles and is primarily diagnosed clinically.

Image summary: This figure consists of clinical photographs. The images display dermatological conditions affecting different parts of the body, specifically showing a large hyperpigmented patch in the axilla and multiple small pitted lesions on the palm of the hand. The presence of these distinct skin manifestations suggests a systemic condition characterized by both pigmentary changes and focal skin atrophy or pitting.

Eschar-Forming Infections

Common feature: eschar formation (black necrotic scab)

• Eschar-forming conditions: Scrub typhus, Cutaneous anthrax, Brown recluse spider bite, Ecthyma gangrenosum

Table summary: The table compares Scrub Typhus and Cutaneous Anthrax across several dimensions, highlighting their distinct causative organisms, modes of transmission involving mites versus animal contact, and their differing clinical presentations of eschars and associated symptoms.

Image summary: This is a clinical photograph. The image shows a skin lesion characterized by a central necrotic ulcer with a dark crust, surrounded by an area of redness and inflammation on the skin surface. The presence of a central eschar surrounded by an erythematous halo suggests a localized tissue death and an inflammatory response, which is often associated with specific types of infections or vascular compromise.

Pseudomonal Infections

• Organism: Pseudomonas aeruginosa

Table summary: The table outlines the distinct clinical presentations and causative pathways for different conditions associated with Pseudomonas infections, ranging from severe necrotic ulcers in immunocompromised individuals to localized skin inflammation from contaminated water and pigment-induced nail discoloration.

Image summary: This figure consists of two side-by-side photographs. The left image shows a close-up of a person's face and neck featuring a dark, irregular skin lesion. The right image depicts a person relaxing in an inflatable hot tub. The juxtaposition of these images suggests a potential correlation between frequent exposure to hot tubs or similar environments and the development of skin abnormalities, implying that certain lifestyle factors or environmental exposures may be linked to skin health issues.

Meningococcemia

• Organism: Neisseria meningitidis

• Fever + neck rigidity + C.N.S symptoms

• Skin: red patches leads to non-blanching on diascopy (cutaneous infarcts)

• Angular cutaneous infarcts (angulated margins)

High Yield

Image summary: This is a clinical photograph. The image shows a skin surface featuring irregular, dark pigmented patches of varying sizes and shapes. The presence of these asymmetric, darkly colored lesions suggests a dermatological condition characterized by abnormal melanin distribution or a pigmented skin disorder.

Ecthyma — Summary

Three Types of Ecthyma

- Ecthyma gangrenosum to Pseudomonas

- Ecthyma pyogenicum leads to Staphylococcus (deeper variant of impetigo)

- Ecthyma contagiosum leads to Parapox virus (Orf virus) leads to goat/sheep handling

Chapter 11: my-ko-bak-teer-ee-ul Infections

Classification of Cutaneous Tuberculosis

• Causative organism: Mycobacterium tuberculosis

• Treatment: Anti-Tubercular Therapy A.T.T (Q)

Table summary: The table categorizes various tuberculosis diseases based on their mode of infection and bacillary status, showing that exogenous and endogenous direct infections can result in either paucibacillary or multibacillary states, while hematogenous infections exhibit variable bacillary status.

Table summary: The table lists various types of tuberculids associated with hypersensitivity, noting that these specific conditions are characterized by negative acid fast bacilli results.

Multibacillary vs Paucibacillary — Memory Trick Dry-looking lesions = Paucibacillary (few bacilli)

Moist-looking lesions = Multibacillary (M for Moist, M for Multi)

T.B.V.C, Lupus vulgaris = dry = P.B | Scrofuloderma = moist = M.B

Tuberculosis Verrucosa Cutis (T.B.V.C)

- Also called anatomist's wart / pathologist's wart

• Post-primary form to prior exposure to T.B bacilli through respiratory system

- Direct inoculation under skin leads to verrucous plaque at contact site

- Common sites: distal acral extremities (Q)

• Paucibacillary (dry-looking lesion)

Image summary: This is a clinical photograph. The image displays a close up view of a human foot, specifically focusing on the heel and sole area, which features a prominent, raised, and textured skin lesion. The lesion is characterized by a rough, cauliflower-like surface with a thickened appearance compared to the surrounding skin. The presence of this hyperkeratotic growth suggests a localized skin condition, such as a plantar wart or a similar dermatological lesion, indicating a proliferation of skin cells in that specific region.

Lupus Vulgaris

Most common form of cutaneous tuberculosis in adults (Q)

• Endogenous (hematogenous) spread

• Paucibacillary (few bacilli, dry-looking)

Table summary: The table describes the clinical features of a skin condition, highlighting the appearance of annular lesions with active edges and central scarring, their common distribution across the face and extremities, and the presence of characteristic apple jelly nodules upon diascopy.

Image summary: This is a clinical photograph. The image shows a close up view of a person's cheek and jawline, featuring a large, raised, reddish plaque that extends from the side of the face toward the cheek. The affected area appears thickened and textured, contrasting with the surrounding healthy skin. The presence of this localized, elevated skin lesion suggests a chronic inflammatory process or a cutaneous infiltration, indicating a pathological skin condition that requires medical diagnosis.

Image summary: This is a clinical photograph. The image displays a large, irregular skin lesion located in the groin area of a male patient, characterized by raised, thickened borders and a central area of altered skin texture. The lesion appears as a plaque with varying degrees of elevation and surface irregularity. The presence of such a lesion in this specific anatomical location suggests a chronic inflammatory or neoplastic dermatological condition requiring medical evaluation.

Scrofuloderma

- Also called tubercular lymphadenitis

• Most common cutaneous T.B in children

• Lymph nodes enlarge to caseation to cold abscess

- Sites: axillary, inguinal, cervical lymph nodes

• Heals with bad ulceration and scar formation

• Multibacillary (moist-looking)

Image summary: This is a clinical photograph. The image shows the upper chest and collarbone area of a person, featuring bilateral skin lesions. There is a prominent, raised, and crusty lesion on the right side and a similar, though slightly less pronounced, lesion on the left side. The presence of these symmetric, ulcerative nodules suggests a systemic or inflammatory condition affecting the skin in these specific anatomical locations.

Table summary: The table compares Erythema Induratum of Bazin with False Tuberculid, highlighting differences in the type of panniculitis, the primary location on the leg, and whether nodules result in ulceration and scarring.

Table summary: This table compares Lichen Scrofulosorum and Lichen Nitidus, highlighting that the former is a hypersensitivity response to Mycobacterium characterized by grouped papules on the trunk that respond to anti-tubercular therapy, while the latter presents as shiny, flat-topped papules in children on the face and extremities that are typically self-resolving.

Table summary: The table compares various diagnostic methods for tuberculosis, categorizing them by detection approach. Direct detection methods include the gold standard culture and histopathology, though culture is noted for being slow. Immune response tests like TST and IGRA show varying levels of sensitivity and specificity. Molecular diagnosis via PCR is highlighted as a rapid and highly sensitive alternative, particularly effective for cases with low bacterial loads.

Chapter 12: Fungal Infections

Dermatophytes

• Dermatophytes are keratinophilic organisms (eat keratin) arrow keratin present in 3 structures: skin, hair, nails

Table summary: The table compares the infection capabilities of different dermatophyte genera across skin, hair, and nails, showing that while all three infect the skin, Trichophyton is the only genus capable of infecting all three sites, whereas Epidermophyton does not infect hair and Microsporum does not infect nails.

Pityriasis Versicolor

• Lesions: both hypopigmented and hyperpigmented (versicolor = versatility)

• Organism: Malassezia globosa (Q) (most common); also M. furfur

Table summary: The table outlines the diagnostic findings for a fungal infection, detailing characteristic clinical scaling, specific growth patterns in culture, fluorescence under a Wood's lamp, and a distinctive microscopic appearance. It also identifies the biological mechanisms responsible for both the lightening and darkening of skin pigmentation.

Image summary: This is a clinical photograph. The image shows a person's skin featuring multiple light-colored, depigmented patches of varying sizes and shapes distributed across the chest area. The presence of these distinct hypopigmented macules suggests a loss of skin pigment, which is characteristic of conditions such as vitiligo or tinea versicolor.

Image summary: This is a clinical photograph. The image displays a person's skin featuring numerous light brown, irregularly shaped patches of varying sizes distributed across the surface. The presence of these multiple cafe-au-lait spots is a characteristic clinical sign often associated with genetic conditions such as neurofibromatosis.

Tinea Corporis

• Annular lesion with central clearing

Tinea incognito (Q): variant with non-classical morphology due to inappropriate use of topical steroids to fungus grows more, itching/inflammation reduces but lesion worsens

Image summary: This is a clinical photograph. The image shows a circular skin lesion characterized by a raised, scaly border surrounding a clearer center. The appearance is consistent with a ringworm infection, suggesting a fungal dermatophytosis of the skin.

Pyt Gold

Image summary: This is a clinical photograph. The image shows the posterior lower torso and upper thighs of a person, featuring multiple circular and irregularly shaped patches of skin discoloration and scaling. These lesions are distributed across the buttocks and extend toward the thighs, characterized by a pale appearance compared to the surrounding skin. The presence of these widespread, well-defined plaques suggests a chronic inflammatory skin condition or a fungal infection affecting the dermal layer.

Tinea Capitis

- Tinea capitis can cause both scarring (kerion, favus) and non-scarring (grey patch, black dot) alopecia

Table summary: The table distinguishes between grey patch and black dot fungal infections based on their growth patterns, the specific organisms involved, and their characteristic visual features.

Table summary: The table compares two types of inflammatory fungal infections, Kerion and Favus, detailing their causative agents and distinct clinical presentations that both lead to scarring alopecia.

Image summary: This is a clinical photograph. The image displays a close up view of a human scalp with dark hair, showing multiple small, raised bumps and areas of redness across the skin surface. The presence of numerous follicular papules and inflammatory lesions suggests a scalp condition characterized by widespread follicular irritation or infection.

Image summary: This figure is a medical photograph. It displays a close-up view of a scalp area characterized by a localized region of significant hair loss and skin texture changes. The image reveals a patch of thinning hair where the skin is more visible compared to the surrounding densely haired areas, indicating a focal area of alopecia.

Image summary: This is a schematic diagram. The figure illustrates two different patterns of fungal spore distribution on hair shafts, labeled as ectothrix and endothrix. In the ectothrix pattern, spores are located on the outer surface of the hair shaft, whereas in the endothrix pattern, spores are contained within the hair shaft. The comparison demonstrates that ectothrix infections involve external colonization of the hair, while endothrix infections are characterized by internal colonization.

Image summary: This is a clinical photograph. The image shows the back of a person's head, featuring a large, irregular area of hair loss on the scalp. This bald patch is characterized by thick, crusty deposits and inflamed skin. The presence of extensive scaling and inflammation within the area of alopecia suggests a severe inflammatory or infectious condition of the scalp.

Image summary: This is a clinical photograph. The image displays a human scalp characterized by extensive hair loss and the presence of numerous yellowish, crusty scales and plaques across the surface. The condition indicates a severe dermatological infection or inflammatory process, resulting in significant scaling and alopecia.

Image summary: This is a clinical photograph. The image shows the back of a person's head, featuring a large, circular area of hair loss on the scalp. The affected region is mostly bald with some sparse hair remaining, while the surrounding areas maintain thick, dark hair. The presence of a well-defined patch of alopecia suggests a localized condition causing significant hair loss in a specific area of the scalp.

Image summary: This is a clinical photograph. The image displays a close-up view of a scalp affected by a skin condition, characterized by the presence of multiple circular, crusty lesions and patches of hair loss. The distribution of these lesions suggests a fungal infection or a similar inflammatory dermatological condition, indicating a widespread impact on the scalp's surface and hair follicles.

Differential Diagnosis of Annular Lesions

Table summary: The table distinguishes between three skin diseases by comparing their central characteristics, peripheral features, and key diagnostic clues.

Deep Fungal Infections

Sporotrichosis (Rose Gardener's Disease) (Q)

• Organism: Sporothrix schenckii (dimorphic fungus: mold at 25 degrees Celsius, yeast at 37 degrees Celsius)

- History: thorn prick (rose gardening)

• Starts as nodulo-ulcerative lesion at inoculation site

- Proximal lymphatic spread to linear lesions to sporotrichoid pattern (Q)

• Histopathology: asteroid body (central yeast surrounded by radiating eosinophilic material)

• Treatment: Itraconazole

Image summary: This figure is a clinical photograph. It displays a series of skin lesions arranged in a linear pattern along the lower limb of a patient. The lesions appear as raised, eroded nodules and ulcers of varying sizes. The linear distribution of these inflammatory skin lesions suggests a sporotrichoid spread, which is characteristic of certain bacterial or fungal infections that travel along the lymphatic vessels.

Chromoblastomycosis (Verrucous Dermatitis) (Q)

• Organisms: pigmented / dematiaceae fungi to Fonsecaea pedrosoi (most common), F. compactum, Phialophora verrucosum

• History: agricultural workers, barefoot walking

• Clinical: cauliflower-like verrucous lesions leads to lower extremities

• K.O.H mount / biopsy: copper penny / Medlar / sclerotic bodies (Q) (brown, round, thick-walled structures to diagnostic)

• Treatment: Itraconazole

Image summary: This is a clinical photograph. The image displays a large, irregular skin lesion on a limb, characterized by a raised, nodular border surrounding a central area of ulceration and crusting. The lesion shows significant tissue proliferation and surface irregularity. The presence of an extensive, ulcerative growth with raised margins suggests a chronic and aggressive pathological process, likely indicating a malignancy or a severe inflammatory condition.

Image summary: This figure is a micrograph image. It displays a collection of spherical biological structures or particles clustered together against a light background. The particles exhibit varying degrees of density and internal structure, with some appearing more hollow and others more solid. The distribution suggests that these entities tend to aggregate rather than remain isolated, indicating a potential affinity for clustering or a shared origin within the sample.

Mycetoma (Madura Foot) (Q)

Image summary: This figure is a photomicrograph of a histological tissue sample. The image displays a cross-section of biological tissue containing several rounded, thick-walled structures, with one specific structure highlighted by an arrow. The presence of these distinct, encapsulated organisms within the tissue indicates a fungal infection, suggesting the colonization of the host tissue by yeast-like pathogens.

• History: thorn prick + barefoot walking

• Two types: Actinomycetoma (bacterial: Actinomadura madurae, Nocardia brasiliensis, Streptomyces somaliensis) and Eumycetoma (Q) (fungal: Madurella mycetomatis, M. grisea)

• Granule color: pale/white granules = mostly actinomycetoma; black granules = mostly eumycetoma (fungal)

Mnemonic

Mycetoma Classic Triad: G.S.T

- G = Granules (macroscopic)

- S = Sinuses (discharging)

- T = Tumor-like swelling

Table summary: The table outlines the distinct treatment approaches for different types of mycetoma, specifying a multi-drug antibiotic regimen for bacterial infections and a progression from antifungal medication to surgical intervention for fungal infections.

Image summary: This is a clinical photograph. The image shows a foot with a large, multinodular growth covering a significant portion of the dorsal surface and extending toward the toes. The growth is characterized by numerous protruding, rounded masses of varying sizes, some of which exhibit surface ulceration and crusting. The growth appears extensive, distorting the normal anatomy of the foot. The presence of these widespread, irregular nodules suggests a severe proliferative skin condition or a neoplastic process affecting the soft tissues of the extremity.

high yield Thorn Prick / Bare foot walking – Differential Diagnosis Thorn prick plus barefoot plus G.S.T triad equals Mycetoma Thorn Prick / Bare foot walking plus cauliflower plus copper penny / sclerotic bodies equals Chromoblastomycosis Verrucous plaque plus acral plus prior T.B exposure equals Tuberculosis Verrucosa Cutis Single verrucous lesion equals Warts (H.P.V) Linear lesions equals Sporotrichosis

Chapter 13: Viral Infections

Table summary: This table compares three viral infections—Herpes Simplex, Varicella, and Herpes Zoster—detailing their causative agents, clinical presentations, characteristic rash distributions, associated complications, diagnostic findings, and respective pharmacological treatments.

Epstein-Barr Virus (E.B.V)

Infectious Mononucleosis (Glandular Fever / Kissing Disease)

• 3 Ps: Pyrexia + Pharyngitis + Posterior cervical lymphadenopathy

• Additional features (differentiating from strep): hepatosplenomegaly

• Posterior cervical chain involvement (vs anterior in streptococcal sore throat)

• Ampicillin/Amoxicillin given to maculopapular rash (Ampicillin rash) (Q)

• Investigations: Monospot test + peripheral smear showing atypical lymphocytes

Image summary: This is a clinical photograph. The image shows a close-up view of human skin featuring a widespread rash characterized by numerous small, reddish spots and patches. The distribution of the rash is dense in some areas and more scattered in others, covering a significant portion of the visible skin surface. The appearance of the skin suggests an inflammatory response or an allergic reaction, indicating a systemic dermatological condition.

High Yield

Infectious Mononucleosis vs Streptococcal Sore Throat Common: Fever + pharyngitis + lymphadenopathy E.B.V: posterior cervical L.N + hepatosplenomegaly + ampicillin rash + monospot + atypical lymphocytes Strep: anterior L.N + palatal petechiae + scarlatiniform rash (sandpaper) + rapid strep antigen test + throat culture

Oral Hairy Leukoplakia O.H.L

• Severely immunosuppressed (H.I.V)

• White corrugated/ridged plaques on lateral border of tongue (Q)

- cannot be scraped off (vs oral thrush which can be scraped off)

Image summary: This is a clinical photograph. The image displays a close up view of oral mucosa featuring a prominent white, undulating, and lace-like pattern of keratotic streaks over a red background. The presence of these reticular white lines suggests a condition such as oral lichen planus, indicating an inflammatory response within the mucosal tissue.

Candidiasis (Oral Thrush)

Most common oral opportunistic infection Inhaled steroids and diabetics are predisposing factors Can be easily scrapped off

Image summary: This is a medical photograph. The image displays a close up view of a tongue surface characterized by a thick yellowish white coating interspersed with numerous small red raised bumps. The presence of these red papillae protruding through a dense white layer suggests an inflammatory condition or a fungal infection of the oral mucosa.

Molluscum Contagiosum

• Caused by Pox virus (Molluscum Contagiosum Virus leads to M.C.V (Q)

Table summary: The table compares the characteristics of MCV-1 and MCV-2, noting that while both present with similar lesion morphology, they differ in their primary sites of infection, with the former affecting the face and trunk in children and the latter affecting the genitals in adults.

• Pseudo-Koebner phenomenon positive

• Histology: Henderson-Patterson bodies (Q) to eosinophilic intracytoplasmic inclusion bodies (diagnostic)

• Treatment: self-limiting; curettage if needed

Image summary: This is a clinical photograph. The image displays several raised, rounded skin lesions of varying sizes distributed across a patch of skin, with the largest lesion featuring a central indentation. The presence of multiple dome-shaped papules with central umbilication suggests a viral skin infection, such as molluscum contagiosum.

Systemic Fungal Infections Mimicking M.C (in H.I.V)

Image summary: This is a clinical photograph. The image displays a close-up view of a person's face, specifically the cheek, nose, and upper lip area, which are covered in numerous small, raised, rounded bumps. These lesions are distributed across the skin and vary slightly in size, with some appearing more prominent than others. The presence of these widespread papules suggests a systemic skin condition or an infectious process characterized by the eruption of multiple nodules across the facial region.

Table summary: The table distinguishes between various conditions based on their characteristic organ involvement and the presence of lesions similar to mucormycosis.

Enteroviral Infections

Table summary: The table compares Herpangina and Hand Foot Mouth Disease, noting that while they share similar etiologies, they differ significantly in the distribution of lesions, with Herpangina being limited to the posterior oropharynx and Hand Foot Mouth Disease affecting the oral cavity as well as the skin of the palms, soles, and buttocks.

Image summary: This is a clinical photograph. The image displays the sole of a foot featuring several small, raised bumps and blisters distributed across the skin. These lesions appear as small nodules or vesicles of varying sizes. The presence of these scattered blisters on the plantar surface of the foot is indicative of a dermatological condition, suggesting a viral or inflammatory skin eruption.

Warts (H.P.V)

Hpv Type Classification

Table summary: This table maps specific HPV types to their associated cutaneous and mucosal diseases, illustrating the diversity of warts and papillomatosis linked to different viral strains.

- Direct skin-to-skin contact leads to multiple verrucous lesions

• Treatment: Salicylic acid (keratolytic arrow peels off stratum corneum), electrocautery, radiofrequency cautery, Cryotherapy

Image summary: This figure consists of two clinical photographs. The images display skin lesions located on the knuckle of a finger in the left panel and on the sole of a foot in the right panel, showing raised, textured growths of varying sizes. The presence of these growths across different anatomical sites suggests a systemic or contagious skin condition characterized by hyperkeratotic lesions.

Genital Warts (Condyloma Acuminata) (Q)

• Anogenital warts equals condyloma acuminata arrow classified as S.T.D

• Condyloma lata = secondary syphilis (different! confusing term)

Low risk H.P.V: 6 and 11 (Q)

• High risk H.P.V: 16 and 18 (Q) leads to squamous atypia / malignancy

• Clinical: verrucous papules/plaques leads to small to large cauliflower-like lesions

• Biopsy: koilocytes (Q) arrow squamous epithelial cells with central hyperchromatic nucleus plus perinuclear halo

Image summary: This figure consists of two clinical photographs. The images display external genital lesions characterized by irregular, cauliflower-like growths and fleshy protrusions on the skin. The presence of these proliferative growths suggests a diagnosis of genital warts, indicating a viral infection of the mucosal and cutaneous surfaces.

Genital Warts in Pregnanc

• Large vulgar warts leads to can cause obstruction of labor

• Infant can acquire laryngeal papillomatosis during birth (H.P.V 6)

Table summary: For non-pregnant individuals, imiquimod is used to treat genital warts by acting as an immunomodulator and TLR7 agonist to facilitate the clearance of the warts.

Table summary: This table outlines treatment options for genital warts based on patient status. For non-pregnant individuals, podophyllin is used to induce necrosis via metaphase arrest. In cases of pregnancy, cryotherapy is the preferred treatment, while imiquimod and podophyllin are strictly contraindicated. Trichloroacetic acid serves as an alternative option through chemical cauterization.

Cutaneous Larva Migrans vs Larva Currens

Table summary: This table compares Cutaneous Larva Migrans and Larva Currens, highlighting that while both involve larval skin penetration, they differ in the causative organism, method of entry, and lesion appearance. Notably, Larva Currens progresses significantly faster than Cutaneous Larva Migrans and requires a simpler medication regimen.

Image summary: This figure consists of two clinical photographs. The images display cutaneous lesions on different parts of the body, showing raised, winding, and linear inflammatory tracks on the skin surface. The appearance of these serpentine patterns suggests a migratory skin condition, indicating the movement of a parasite beneath the epidermis.

Scabies

• Organism: Sarcoptes scabiei var hominis (Q) (mite)

Morphology: 2 pairs anterior legs + 2 pairs posterior legs

• Typical load: 10 to 12 mites

• Incubation period: 4 weeks

• Transmission: skin-to-skin contact or fomites

Hallmark Lesion

• Burrows (Q) to serpiginous tunnels in the stratum corneum containing the mite and scybala (fecal matter)

Classic distribution: Circle of Hebra (web spaces, flexor wrists, axillae, umbilicus, groin)

Image summary: This is a clinical photograph. The image displays a close-up view of skin with several small, raised lesions indicated by arrows. The presence of these growths on the skin surface suggests a dermatological condition, specifically consistent with the appearance of genital warts as indicated by the context.

Table summary: This table outlines distinct clinical presentations of scabies across different patient groups. It highlights how adults typically spare the face due to the protective nature of sebum, whereas infants exhibit facial and extremity involvement because their sebaceous glands are inactive. It further distinguishes animal scabies by the absence of burrows and describes crusted scabies in immunocompromised individuals as a severe manifestation characterized by a massive increase in mite population, a lack of itching, and significant skin thickening.

Image summary: This figure consists of two clinical photographs. The images display skin manifestations on a patient, specifically showing a widespread rash on the face and pustular lesions on the sole of the foot. The distribution and appearance of these cutaneous lesions are characteristic of the inflammatory response associated with trypanosomiasis.

Treatment of Scabies

Table summary: This table outlines recommended safe treatment options for scabies across different patient populations. It suggests a combination of topical and oral medications for general cases and Norwegian scabies, while specifying a limited set of safe topical agents for infants and pregnant women, explicitly noting that certain treatments are contraindicated or unstudied for pregnancy.

Table summary: Permethrin and sulfur ointment are identified as high yield treatment options because they are safe for use in both infants and pregnant women.

Pediculosis (Lice Infestations)

Table summary: The table compares different types of lice infestations, detailing their distinct clinical presentations and preferred treatment strategies, ranging from topical applications to environmental disinfection and partner notification.

Table summary: This table compares the characteristics of American and African trypanosomiasis, highlighting differences in the causative organisms, the insect vectors responsible for transmission, and the distinct clinical signs associated with each disease.

Image summary: This figure consists of two clinical photographs. The first image shows a person with significant swelling and inflammation of the left eyelid and surrounding orbital area, while the second image displays a prominent lump or swelling on the side of the neck, highlighted by a circle. These clinical signs indicate the presence of systemic infection and lymphadenopathy, which are characteristic manifestations of Trypanosomiasis.

Post-Kala-Azar Dermal Leishmaniasis (P.K.D.L)

• Organism: Leishmania donovani

• History of prior visceral leishmaniasis (kala-azar) (Q)

• Cutaneous lesions mimicking lepromatous leprosy to hypopigmented macules on trunk

• Patients act as asymptomatic reservoir for the parasite

Differentiating P.K.D.L from Lepromatous Leprosy

Table summary: The table compares clinical features of PKDL and Lepromatous leprosy, highlighting that PKDL is characterized by the presence of LD bodies on slit-skin smears with normal sensation and no nerve thickening, whereas Lepromatous leprosy shows acid-fast bacilli, nerve thickening, and decreased sensation.

• Treatment: Miltefosine (especially in Bihar where P.K.D.L is endemic)

Image summary: This is a clinical photograph. The image displays a person's back featuring numerous light-colored, depigmented patches of varying sizes scattered across the skin. The presence of these hypopigmented lesions is characteristic of the cutaneous manifestations associated with trypanosomiasis.

Image summary: This is a clinical photograph. The image displays a close-up view of a person's face, specifically focusing on the nose, mouth, and chin area, which exhibit extensive skin lesions and swelling. The presence of these cutaneous abnormalities and facial inflammation indicates a severe systemic infection, consistent with the diagnosis of trypanosomiasis.

Chapter 15: Hansen's Disease (Leprosy)

Ridley-Jopling Classification P.Y.T Gold

Table summary: This table compares the clinical and histological characteristics of the two poles of the Ridley-Jopling classification for leprosy. The tuberculoid pole is characterized by strong cell-mediated immunity, positive lepromin tests, few well-defined skin lesions, and paucibacillary smears. In contrast, the lepromatous pole exhibits poor or absent immunity, negative lepromin tests, widespread ill-defined lesions, and multibacillary smears. Histologically, the tuberculoid form presents with epithelioid granulomas, while the lepromatous form is marked by foamy macrophages and a distinct subepidermal uninvolved zone.

Image summary: This is a schematic diagram. The figure illustrates the histological distribution of cells and granulomatous structures within a tissue section, specifically representing a Ridley-Jopling subtype of leprosy. The illustration shows clusters of epithelioid cells and lymphocytes forming granulomas, with some areas showing a higher density of inflammatory infiltrates compared to others. It can be inferred that the tissue exhibits a chronic inflammatory response characterized by the formation of organized cellular aggregates, indicating a specific immunological reaction to an infectious agent.

Image summary: This figure is a medical illustration. It depicts a collection of cells with distinct nuclei distributed across a tissue background. The arrangement shows a moderate density of cells that are relatively uniform in size and shape, suggesting a specific histological pattern associated with a disease subtype.

Nerve Involvement and Key Features

Table summary: The table outlines key diagnostic and clinical features of the condition, identifying the most frequently affected cranial and peripheral nerves, the specific type of sensory loss that occurs first, and the preferred staining method for detecting bacilli.

Image summary: This is a clinical photograph. The image displays a close-up view of human skin featuring several raised, nodular lesions and a linear, thickened area of skin indicated by an arrow. The presence of these distinct skin morphologies suggests a dermatological condition characterized by both localized nodules and broader plaque-like infiltration, consistent with the varied presentations of the Ridley-Jopling classification for leprosy.

Table summary: This table outlines the Ridley-Jopling subtypes of leprosy, detailing the progression of lesion appearance and key clinical features across a spectrum of immune responses. It contrasts the localized, well-defined plaques associated with strong immunity in tuberculoid forms against the diffuse, symmetrical infiltration and widespread nerve involvement characteristic of lepromatous forms, while identifying the mid-borderline type as the most unstable manifestation.

Image summary: This is a clinical photograph. The image displays a skin lesion characterized by an oval, ring-shaped area of inflammation with a raised, scaly border and a relatively clear center. The appearance suggests a chronic inflammatory skin condition, indicating a localized dermatological reaction with peripheral expansion.

Image summary: This is a clinical photograph. The image shows a circular, reddish skin lesion with a slightly raised border and a central area that appears somewhat clearer than the edges. The lesion exhibits an annular pattern, suggesting a localized inflammatory or infectious skin condition.

Image summary: This is a medical photograph. The image displays a skin lesion on a human body part, characterized by a large, irregular patch of discoloration with a distinct central area that differs in tone from the surrounding perimeter. The lesion exhibits a textured surface and defined borders, suggesting a dermatological condition consistent with the Ridley-Jopling classification of leprosy.

Lepromatous Leprosy — Clinical Features

• Route of infection: inhalation

• Earliest signs: epistaxis + nasal crusting (at respiratory entry site)

• Autonomic failure: pedal edema

• Leonine facies (lion-like face arrow diffuse facial infiltration)

• Madarosis (loss of eyebrows)

• Glove and stocking pattern of anesthesia

• Trophic ulcers (trauma from anesthesia leads to painless ulcers)

• Corneal anesthesia (trigeminal nerve) to

Lagophthalmos (facial nerve leads to inability to close eyes)

• Claw hand deformity (ulnar nerve involvement)

Image summary: This is a clinical photograph. The image depicts a person's face and ear, showing widespread skin abnormalities characterized by numerous raised nodules and thickened skin. These growths are most prominent on the cheeks, chin, nose, and the outer rim of the ear. The distribution of these lesions suggests a systemic dermatological condition that causes significant distortion of the facial features and ear structure.

Who/Nlep Classification and Treatment

Table summary: This table compares paucibacillary and multibacillary leprosy, showing that multibacillary cases are characterized by a higher number of skin lesions, nerve involvement, and positive skin smears, which consequently requires a longer duration of treatment compared to paucibacillary cases, while the medication dosages remain consistent for both.

• Clofazimine side effect: hyperpigmentation (Q) (reddish-brown skin discoloration)

Image summary: This is a photograph of pharmaceutical blister packaging. The image displays multiple rows and columns of capsules and tablets organized within a plastic and foil sheet, featuring branding from a pharmaceutical company and specific storage instructions. The packaging indicates that the medication is provided free of charge and is intended exclusively for the treatment of leprosy, suggesting it is part of a specialized public health initiative.

Spontaneous Remission

Image summary: This is a photograph of a medication blister pack. The image displays a multi-drug therapy kit for adults, featuring a structured layout of individual pill compartments organized by day. The packaging includes dosage instructions and branding from pharmaceutical companies and health organizations. The layout indicates a sequential daily regimen designed to ensure patient compliance over a period of several weeks, suggesting a long-term treatment course for a specific medical condition.

• 95% of leprosy cases resolve spontaneously after bacillus exposure

• More common in: indeterminate greater than tuberculoid (Q); adults greater than children

Lepra Reactions (Acute Inflammatory Episodes)

Mnemonic

Rule of 5 for Lepra Reactions

- Type 1: Type 4 (delayed, cell-mediated) hypersensitivity leads to 1 plus 4 equals 5

- Type 2 E.N.L: Type 3 (immune complex) hypersensitivity to 2 + 3 = 5

B.L is common to both reactions

Table summary: This table compares Type 1 and Type 2 lepra reactions, highlighting that Type 1 is a delayed hypersensitivity reaction affecting existing lesions and nerves, whereas Type 2 is an immune complex reaction characterized by new systemic nodules and widespread organ involvement. While both are managed with prednisolone and the continuation of multi-drug therapy, Type 1 may require surgical drainage for severe nerve abscesses.

Image summary: This is a clinical photograph. The image shows a close-up view of a person's face, specifically focusing on the cheek and area around the eye, which exhibits a raised, reddish swelling and skin inflammation. The presence of a localized, erythematous plaque on the cheek suggests an inflammatory skin condition or a subcutaneous lesion.

Image summary: This is a clinical photograph. The image displays a section of skin characterized by multiple raised, reddish nodules and papules of varying sizes distributed across the surface. These lesions appear inflamed and are interspersed with areas of skin that show general redness and irritation. The presence of numerous firm, elevated bumps suggests a chronic inflammatory condition or an infectious process affecting the dermal layers.

Prophylaxis and Vaccination

Table summary: The table outlines different modalities for leprosy prevention and treatment, contrasting immunotherapy via Mycobacterium indicus pranii for prophylaxis and bacilli clearance with chemoprophylaxis using a single dose of Rifampicin for eligible contacts.

Chapter 16: Sexually Transmitted Infections

Pyt Gold

Painless Genital Ulcers

Table summary: The table compares different sexually transmitted infections by identifying the specific causative organisms responsible for syphilis, lymphogranuloma venereum, and donovanosis.

Table summary: This table compares the clinical presentations of different genital ulcers, contrasting their physical characteristics, lymph node involvement, incubation periods, and diagnostic markers. It distinguishes between painless, hard ulcers with bilateral painless lymphadenopathy and painful, soft ulcers with unilateral suppurating buboes, while also noting specific diagnostic findings such as the groove sign and characteristic staining patterns.

Table summary: The table compares the causative organisms for two types of painful genital ulcers, distinguishing between the specific bacterium responsible for chancroid and the various strains of the herpes simplex virus that cause genital herpes.

Image summary: This figure is a diagnostic flowchart. It outlines the clinical classification of ulcers based on their presentation and the condition of associated lymph nodes. The chart branches into two primary paths: one for single, painless ulcers and another for multiple, painful ulcers. For single, painless ulcers, the path further divides based on lymph node involvement, distinguishing between bilateral painless nodes and unilateral or bilateral nodes that develop into painful buboes. For multiple, painful ulcers, the path distinguishes between those with unilateral buboes that are painful and non-suppurative, and those with bilateral nodes that show no such reaction. The flowchart concludes that while the initial ulcer may be painless, the subsequent lymph node reaction can be painful, whereas painful ulcers are typically associated with painful, non-suppurative lymph node swelling.

Genital Ulcer to Painful or Painless?

- Painful plus multiple plus bubo arrow Chancroid

- Painful plus grouped vesicles plus no bubo leads to Herpes genitalis

- Painless plus bilateral shotty L.N leads to Syphilis

- Painless plus bubo plus groove sign leads to L.G.V

- Painless plus beefy red plus L.N not involved leads to Donovanosis

N.A.C.P Syndromic Management Kits

Mnemonic

Kit Colors: “Grey Girl Wearing Bracelet Reading Yellow Book” 1 equals Grey | 2 equals Green | 3 equals White | 4 equals Blue | 5 equals Red | 6 equals Yellow | 7 equals Black | 8 equals Brown

Table 3.9 summary: This table outlines the various color-coded medication kits provided under the NACP for treating different sexually transmitted infection syndromes. Each kit contains a specific combination of medications tailored to target particular symptoms, such as urethral or vaginal discharge, genital ulcers, lower abdomen pain, and anorectal discharge, with some kits providing alternative treatments for patients with specific allergies.

Gonococcal vs Non-Gonococcal Urethritis

• Gonococcal: Neisseria gonorrhoeae leads to Gram stain: intracellular diplococci (Q) leads to Investigation of choice: N.A.A.T

- Non-gonococcal: Chlamydia leads to white blood cells only on Gram stain (Chlamydia does not show up)

• Drug resistance most seen with: Gonorrhoea (Q)

Syphilis Treatment

Table summary: The table outlines the treatment protocols for different stages of infection under NACP, specifying that early stages receive a single dose of intramuscular benzathine penicillin, while more advanced or late stages require a multi-week course of the same medication.

Table summary: This table outlines the recommended penicillin-based treatment regimens for neurosyphilis and congenital syphilis under NACP guidelines, while specifying doxycycline as the alternative for patients with penicillin allergies.

• Condyloma acuminata (H.P.V anogenital warts) versus Condyloma lata (secondary syphilis leads to moist, broad-based genital lesions) leads to important differentiation

Chapter 17: Connective Tissue Disorders

Discoid Lupus Erythematosus (D.L.E)

• Location: photo-exposed areas to face, scalp, ears

• Lesions: discoid shape + peripheral hyperpigmentation + central depigmentation/atrophy

• Scarring alopecia on scalp

• Carpet tack sign (Q): follicular plugging (scales have horny projections on undersurface)

• Schuster's sign: D.L.E lesion on the concha of the ear

Image summary: This is a clinical photograph. The image displays a close-up view of a person's scalp and forehead area, showing a raised, pale skin lesion located near the hairline. The presence of this distinct growth suggests a localized skin abnormality or lesion that differs in texture and appearance from the surrounding skin.

Image summary: This is a clinical photograph. The image shows a close up view of a human ear and the adjacent side of the face, focusing on the external auditory canal and the surrounding skin. There is evidence of abnormal skin growth and tissue irregularity within the ear canal and extending toward the cheek, suggesting a pathological condition or lesion.

Systemic Lupus Erythematosus (S.L.E)

- Classic sign: Malar rash (butterfly rash) over cheeks and nasal bridge

- Key differential: malar rash in S.L.E spares nasolabial folds (Q) (unlike rosacea and dermatomyositis where nasolabial folds are involved)

• Photosensitivity

• Painless oral ulcers

• Alopecia (can be both scarring and non-scarring)

• Joint pains

• Hematological abnormalities

Image summary: This is a medical illustration. The figure depicts a person's face showing a distinct rash that spans across the bridge of the nose and extends over both cheeks. The distribution of the skin inflammation forms a characteristic shape resembling a butterfly, which is a clinical sign often associated with specific autoimmune conditions.

Table summary: This table outlines the characteristic cutaneous manifestations of dermatomyositis, detailing specific diagnostic signs such as purplish rashes around the eyes, pathognomonic papules on the finger joints, and distinct erythematous patterns across the upper back, shoulders, and neck.

- Proximal muscle weakness (difficulty climbing stairs, getting up, combing hair)

• Association with malignancy (important in adults arrow search for underlying malignancy)

• Gorlin sign is not associated with dermatomyositis (Q)

Image summary: This figure consists of two clinical photographs. The left image shows a person's face focusing on the eyes and nose, highlighting a purple tint and swelling around the eyelids. The right image displays the back of a hand with raised, scaly patches over the knuckles. These clinical signs, specifically the characteristic eyelid discoloration and the skin lesions on the joints of the fingers, are indicative of dermatomyositis.

Morphea (Localized Scleroderma)

• Localized form of scleroderma (skin thickening without systemic involvement)

• Special variant: En coup de sabre to linear morphea on the forehead (looks like a sword strike)

• Histology: Box sign (Q) to biopsy gross morphology looks like a box (scanner view)

Image summary: This is a clinical photograph. The image shows a close up view of a person's forehead and hairline, featuring a vertical linear area of skin discoloration and texture change extending from the brow up into the scalp. The presence of this cutaneous manifestation in the context of the provided caption indicates a clinical presentation of dermatomyositis.

Image summary: This figure is a histopathological micrograph. It displays a cross-section of skin tissue, showing the epidermis at the top, a thick layer of dermis in the middle, and subcutaneous adipose tissue at the base. The image reveals an inflammatory infiltrate within the dermal layer, characteristic of dermatomyositis, where immune cells are distributed throughout the connective tissue.

Scleroderma (Systemic Sclerosis)

• Skin involvement + organ involvement (systemic)

Table summary: The table describes the characteristic cutaneous features associated with dermatomyositis, detailing the specific appearance and physiological changes of skin pigmentation, finger skin texture, vascular responses in the digits, and surface blood vessel dilation.

High Yield

Image summary: This is a clinical photograph. The image shows a close up view of the skin on the upper back and neck area, which is covered in numerous small, dense, brownish papules. The distribution of these lesions is widespread across the affected area, appearing as a textured rash. The presence of these skin manifestations is characteristic of dermatomyositis, indicating an inflammatory condition affecting both the skin and muscles.

Malar Rash Differential

- S.L.E: nasolabial folds Spared

- Rosacea: nasolabial folds Involved + telangiectasias + no comedones

- Dermatomyositis: heliotrope rash (periorbital) + Gottron's papules

Chapter 18: Drug Reactions / Drug Eruptions

Fixed Drug Eruption F.D.E

• Most common drug: N.S.A.I.D's (Q) (painkillers); also cotrimoxazole, metronidazole, tetracyclines

• Fixed eruption at a fixed site to recurs at the exact same site upon re-exposure to the same drug

- Sites: face, genitals, lower lip

hyperpigmentation (Q)

Image summary: This is a clinical photograph. The image displays a localized, circular skin lesion on the abdominal area near the navel, characterized by a dark central discoloration surrounded by a reddish perimeter. The presence of this specific skin manifestation in the given context indicates a systemic inflammatory condition affecting the skin and muscles.

Image summary: This is a clinical photograph. The image shows a close-up view of a person's lips, specifically highlighting a dark, purplish discoloration on the upper lip. The discoloration is uneven and concentrated on one side of the upper lip, contrasting with the natural tone of the lower lip. The presence of this pigmentation in the context of the provided caption suggests a cutaneous manifestation associated with dermatomyositis.

Erythema Multiforme E.M.F

- Classic lesion: target lesion / bull's eye appearance (Q)

• Concentric rings: center erythematous leads to pale edema leads to peripheral erythema

- Classic sites: palms, soles, distal extremities

• Most common cause: Herpes Simplex Virus 1 H.S.V-1

(Q) (infection-driven, not primarily drug-driven)

Image summary: This figure is a clinical photograph. It displays a close-up view of the skin on a palm, characterized by multiple reddish, circular lesions and patches of inflammation across the surface. The presence of these distinct erythematous papules on the palmar surface is indicative of dermatomyositis, suggesting a systemic inflammatory condition affecting the skin.

Stevens-Johnson Syndrome (S.J.S) and Toxic Epidermal Necrolysis (ten)

Table summary: The table compares Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis, showing that the latter is characterized by more extensive body surface area involvement and more severe epidermal detachment, while both share a positive pseudo Nikolsky sign and differ in their overall prognosis.

High Yield

S.J.S vs ten — Key Differentiator

- S.J.S: less than 10% body surface area involvement

- Overlap: 10 to 30% body surface area

- ten: more than 30 percent body surface area to sheet-like peeling to score-ten for prognosis

Image summary: This is a clinical photograph. The image shows a close up view of human lips and the surrounding skin, which exhibit significant inflammation, crusting, and widespread reddish spots. The lips appear swollen with dark, hemorrhagic crusts, and the adjacent facial skin is covered in numerous small, scattered lesions. These findings indicate a severe inflammatory or infectious condition affecting the mucosal and cutaneous surfaces of the mouth area.

Image summary: This is a clinical photograph. The image shows a person's back and shoulder area exhibiting widespread skin abnormalities, including numerous dark spots and large areas where the top layer of skin has peeled away, exposing raw underlying tissue. The distribution of the skin loss is irregular and extensive across the upper back. These findings indicate a severe dermatological condition characterized by widespread epidermal detachment and significant skin damage.

Drug-Induced Pigmentation

Table summary: This table outlines the distinct pigmentary changes associated with various drugs, detailing the characteristic colors and primary anatomical locations or clinical features for each medication.

Chapter 19: Systemic Dermatology

Acanthosis Nigricans

Table summary: The table outlines the clinical characteristics of a condition, highlighting its typical appearance as dark, velvety plaques located in skin folds, and its associations with metabolic disorders and certain malignancies.

Image summary: This is a clinical photograph. The image displays a close up view of a human axilla showing significant skin thickening and darkening. The skin exhibits a velvety texture with prominent linear creases and deep folds. These physical characteristics are indicative of acanthosis nigricans, a skin condition often associated with insulin resistance or other systemic endocrine disorders.

Granuloma Annulare

• Annular (ring-like) arrangement of beaded, smooth papules with central clearing

- Location: dorsum of extremities (backs of hands and feet)

• Associated with diabetes mellitus (Q)

- Differential: tinea corporis arrow but granuloma annulare has no scaling and no itching (unlike tinea)

Image summary: This is a clinical photograph. The image shows the back of a human hand featuring several raised, reddish, and scaly skin lesions of varying sizes. The distribution of these plaques is concentrated across the dorsal surface of the hand and extends toward the knuckles. The presence of these well-defined, erythematous patches suggests an inflammatory skin condition or a dermatological disorder characterized by plaque formation.

Necrobiosis Lipoidica Diabeticorum

• Presentation: waxy, yellow, atrophic plaques

- Site: anterior aspect of shin (leg)

• Dilated blood vessels (telangiectasia) visible through atrophic skin

• Can ulcerate

• Important association: diabetes mellitus (Q)

Image summary: This is a clinical photograph. The image shows a lower leg with a large area of skin inflammation and scarring, featuring several open ulcers with yellowish exudate and surrounding redness. The presence of chronic skin changes and ulceration suggests a condition such as venous insufficiency or a chronic inflammatory skin disorder leading to tissue breakdown.

Pretibial Myxedema

• Important association: Graves disease (Q)

• Clinical: non-pitting edema to skin-colored / waxy nodules over pretibial area

• Peau d'orange appearance (orange peel-like skin texture)

High Yield

Image summary: This is a clinical photograph. The image shows the lower legs and feet of a person, displaying bilateral swelling and skin discoloration. There is noticeable redness and scaling, particularly on the lower portions of the shins and ankles. The skin appears thickened and inflamed, suggesting a chronic inflammatory process or circulatory issue affecting both limbs.

Diabetes-Associated Skin Conditions

- Acanthosis nigricans leads to velvety axillary plaques plus insulin resistance

- Granuloma annulare leads to annular papules on dorsum of extremities plus no scaling

- Necrobiosis lipoidica leads to waxy yellow atrophic shin plaques plus can ulcerate

All three associated with diabetes mellitus Chapter 20: Nutritional Dermatology

Phrynoderma ("Toad Skin")

- Deficiency of: Vitamin A, B, C, and E (Q) arrow but not vitamin D

• Essential fatty acid deficiency can also produce this condition

• Clinical: follicular hyperkeratosis (horny papules) arrow described as “toad skin”

- Sites: extensor surfaces of extremities (thighs, upper arms)

• Exam question: patient with papular lesions to

- Exam question: patient with papular lesions leads to investigation leads to send for ophthalmology referral (Q) (to check for vitamin A deficiency eye changes, not vitamin D levels)

Pellagra

Image summary: This is a clinical photograph. The image shows a close up view of a person's elbow featuring a dense cluster of small, raised, skin colored bumps. The distribution of these papules is concentrated on the extensor surface of the joint. The presence of numerous small nodules in a localized area suggests a dermatological condition characterized by follicular or papular eruptions.

• Deficiency: Niacin (Vitamin B.3 (Q)

• Risk factors: diet based on jowar (sorghum) or maize (corn), and Alcoholism

• Clinical signs: Photodermatitis, Casal's necklace (dermatitis around the neck)

- Dementia

- Diarrhea (completing the classic "3 Ds" of Pellagra).

Image summary: This is a clinical photograph. The image shows a person with significant skin alterations affecting the face, neck, and upper chest, characterized by thickened, darkened, and textured skin patches. The distribution of these lesions suggests a chronic dermatological condition resulting in skin hardening and discoloration across the central facial area and extending down the neck in a broad band.

Acrodermatitis Enteropathica

• Pathology: Defective Zinc absorption (due to a mutation in the S.L.C.3.9.A.4 gene; Autosomal Recessive - A.R.

• Onset: Classically presents during the weaning of a child from breast milk.

• Clinical Signs:

- Periorificial (around mouth/anus) and acral dermatitis

- Alopecia

- Diarrhea

• Management: Lifelong zinc supplementation.

Image summary: This figure consists of two side-by-side clinical photographs. The images show an infant before and after a medical intervention, focusing on the skin of the torso, face, and limbs. The first image displays widespread, dense skin eruptions and inflammation across the body, while the second image shows the same infant with a significant reduction in skin lesions and a clearer complexion. It can be inferred that the treatment administered was highly effective in resolving the dermatological condition.

Scurvy

• Deficiency: Vitamin C (Q)

• Collagen not formed properly to blood vessel fragility

• Bleeding gums (scorbutic gums)

• Hair changes: Corkscrew hair

• Perifollicular hemorrhage

Image summary: This figure consists of two clinical photographs. The left image shows a close up of a patient's lower teeth and gums, while the right image is a magnified dermatoscopic view of a skin lesion. The dental image reveals significant gum inflammation and recession around several teeth, accompanied by tooth decay and misalignment. The skin image shows a localized area of redness and irritation on the skin surface. The figure suggests a systemic condition manifesting as both periodontal disease and cutaneous inflammation, indicating a possible correlation between the oral and skin pathologies.

Chapter 21: Malignancies & Skin

Seborrheic Keratosis

• Appearance: “Stuck-on” appearance (Q) to waxy, verrucous plaques

- Sites: mainly trunk, in elderly individuals

• Paraneoplastic sign: sudden eruption of multiple seborrheic keratoses to Sign of Leser-Trélat (Q) to associated with internal malignancy (especially gastric adenocarcinoma)

• Seborrheic keratosis will not transform into squamous cell carcinoma ("S cannot turn into S")

Image summary: This is a clinical photograph. The image displays the posterior torso of a person showing numerous scattered, hyperpigmented macules and papules of varying sizes across the back. The distribution of these lesions is widespread, with some appearing as small spots and others as larger, coalescing patches. The presence of multiple brown pigmented lesions across a large surface area suggests a systemic dermatological condition characterized by widespread pigmentary changes.

Cutaneous Horn

• Conical, hard, hyperkeratotic projection resembling an animal horn

Morphological description, not a diagnosis

• Base must be biopsied to can harbor premalignant (actinic keratosis) or malignant (squamous cell carcinoma) conditions

Image summary: This figure is a close-up photograph. It displays a curved, horn-like cutaneous growth protruding from the skin of a biological subject. The growth exhibits a textured, layered surface and a tapered end. The presence of this growth indicates a cutaneous horn, which is a hard protrusion of keratinized material resulting from an abnormal accumulation of skin cells.

Kaposi Sarcoma

• Vascular tumor to seen in immunocompromised / H.I.V patients (Q)

• Clinical: purple-colored plaques and nodules

• Associated with H.H.V-8 (Q)

- H.H.V-8 also causes: Castleman disease + primary effusion lymphoma

Image summary: This is a clinical photograph. The image displays a close up view of human skin affected by numerous reddish purple lesions of varying sizes. These lesions appear as raised bumps and flat patches that are scattered across the skin surface. The presence of these widespread, hemorrhagic-looking skin lesions suggests a systemic condition or a severe dermatological reaction characterized by blood leaking into the skin.

Image summary: This is a clinical photograph. The image shows an open mouth revealing a large, multinodular, and fleshy growth that occupies a significant portion of the oral cavity, extending across the palate and towards the throat. The growth exhibits a cobblestone appearance with multiple rounded protrusions. The presence of this extensive mass suggests a severe proliferative condition or a neoplastic growth that is obstructing the oral passage and displacing normal anatomical structures.

Actinic Keratosis

• Premalignant condition leads to due to chronic sun damage

- Rough, scaly, erythematous patches on sun-exposed skin (face, scalp, forearms)

• If left untreated to may transform into squamous cell carcinoma (Q)

Image summary: This is a clinical photograph. The image shows the top of a person's head, exhibiting significant hair loss and multiple skin lesions. These lesions appear as irregular patches of redness and open sores across the scalp. The presence of these widespread skin abnormalities and the loss of hair suggest a severe dermatological condition or a systemic medical issue affecting the scalp.

Basal Cell Carcinoma

- Initially: pearly nodule with surface telangiectasia

• Ultimately ulcerates to “Rodent ulcer” with rolled-out edges (Q)

- Site: above the line joining angle of mouth to tragus to elderly individuals

• Pathology: mutations in Sonic Hedgehog S.H.H pathway (Q)

• Treatment: Vismodegib (Hedgehog pathway inhibitor); surgical: Mohs micrographic surgery

• Histopathology: palisading granuloma / palisading basaloid nests

Image summary: This is a clinical photograph. The image displays a raised, rounded skin lesion on a surface of skin. The lesion appears as a nodule with a smooth surface and some internal vascular patterns. The presence of a distinct, elevated growth suggests a localized skin condition or a benign or malignant neoplasm that requires medical evaluation.

Image summary: This is a clinical photograph. The image shows a close up view of a human ear and the adjacent side of the face, featuring a large, irregular open wound with raw tissue and crusting that extends from the ear canal onto the cheek. The lesion appears invasive, causing significant tissue destruction and surface irregularity, suggesting a severe inflammatory or neoplastic process.

Image summary: This figure is a histological diagram. It depicts a cross-section of biological tissue showing a surface layer of epithelial cells overlying a deeper layer of connective tissue containing glandular structures. The image illustrates the arrangement of cells and the interface between the surface lining and the underlying secretory units. It can be inferred that the tissue is designed for both protection at the surface and secretion within the deeper layers, characteristic of a mucosal membrane.

Mycosis Fungoides

Most common type of cutaneous T-cell lymphoma (Q)

• Despite the name to not a fungal infection to it is a malignancy

• 4 clinical stages: Patch leads to Plaque leads to Tumor leads to Erythroderma

• Histopathology: epidermotropism (atypical T-lymphocytes migrate from dermis into epidermis) + Pautrier's microabscess (Q)

Sézary Syndrome

• Leukemic / systemic variant of mycosis fungoides

• 3 features: Sézary cells (atypical T-cells with cerebroform nucleus in blood) + generalized lymphadenopathy + erythroderma

Image summary: This is a photomicrograph of a peripheral blood smear. The image displays numerous red blood cells surrounding a single, centrally located white blood cell with a distinctively lobulated nucleus, indicated by an arrow. The presence of this multi-lobed nucleus within the leukocyte suggests that the cell is a neutrophil, which is characteristic of a normal immune response or specific hematological conditions.

Malignant Melanoma

• Etiology: U.V / actinic damage in genetically predisposed individual

• Gene: C.D.K.N.2.A (cyclin-dependent kinase inhibitor 2.A

• Risk factors: U.V exposure + giant congenital melanocytic nevus (more than 20 centimeters)

Table summary: The table outlines the distinguishing characteristics of various melanoma subtypes, highlighting their prevalence in specific demographics, growth patterns, and overall clinical prognosis.

Mnemonic

Melanoma A.B.C.D.E Criteria A = Asymmetry | B = Border irregularity | C = Color variation | D = Diameter more than 6 millimeters | E = Evolution (change over time)

Image summary: This is a clinical photograph. The image displays a pigmented skin lesion on a person's skin, characterized by an irregular shape and uneven distribution of pigment. The lesion shows significant asymmetry and variation in tone, with a very dark area on one side and lighter, more diffused brown areas extending toward the other side. The irregularity in both color and border suggests an atypical growth, which is often a clinical indicator for further dermatological evaluation to rule out malignancy.

Xeroderma Pigmentosum

• Pathogenesis: defect in nucleotide excision repair N.E.R (Q)

• Inability to repair U.V-induced D.N.A damage leads to accumulation of mutations which leads to genomic instability

• Clinical: dry skin (xeroderma) plus pigmentation leads to extensive freckling/lentigines on sun-exposed areas

• High risk of developing squamous cell carcinoma, basal cell carcinoma, melanoma

• Autosomal recessive inheritance

Image summary: This is a composite photograph. The image displays a close up of an adult's face covered in extensive dark pigmentation and spots, while a hand holds a small childhood photograph over one side of the adult's face. The contrast between the childhood photo and the current state of the skin suggests a progressive dermatological condition that developed over time, indicating a significant change in skin appearance from childhood to adulthood.

Chapter 22: Short Topics in Dermatology

Neutrophilic Dermatoses

• Sweet syndrome and Pyoderma gangrenosum are both classified as neutrophilic dermatoses to common histopathological feature: neutrophilic infiltration in the dermis

Table summary: This table compares Sweets syndrome and Pyoderma gangrenosum across their respective etiologies and clinical presentations, highlighting that the former is associated with infections and hematologic malignancies presenting as tender papules and plaques, while the latter is linked to inflammatory bowel disease and rheumatoid arthritis presenting as progressive cutaneous ulcers.

Table summary: The table compares Cutis marmorata and Erythema Ab igne, contrasting a physiological response to cold in neonates with a heat-induced skin reaction caused by constant exposure to heat sources.

Dermatitis Artefacta

• Psychocutaneous disorder (factitial dermatitis) to self-inflicted lesions

- Distribution: accessible areas only (dominant hand can reach) leads to inaccessible areas (mid-back) spared

- Bizarre lesions that do not fit into any known disease pattern

• Attention-seeking behavior to commonly seen in prisoners or patients with underlying psychiatric conditions

Image summary: This is a clinical photograph. The image displays a close up view of a man's face showing multiple superficial skin lesions and abrasions across the cheeks and under the eyes. The distribution of the injuries is bilateral and concentrated on the mid-face region. The presence of these scattered skin breaks suggests a history of blunt force trauma or superficial scratching to the facial area.

Netherton Syndrome

• Gene: spink5 mutation (encodes lekti protein) leads to autosomal recessive

• Hair change: bamboo hair (trichorrhexis invaginata) (Q) arrow ball-and-socket joint appearance of hair shaft

• Triad: atopic dermatitis (eczematous skin) + ichthyosis linearis circumflexa (migratory serpiginous scaly plaques with double-edge

serpiginous scaly plaques with double-edged scale) + bamboo hair

Image summary: This figure is a photomicrograph. It displays a magnified view of a biological specimen, showing a dark, elongated structure with a widened, bifurcated section. The image reveals a dense internal composition and a textured outer boundary. The morphology suggests a specialized anatomical feature of a microscopic organism, characterized by a distinct branching pattern and a concentrated central mass.

Trichothodystrophy

• Autosomal recessive leads to defect in sulfur-containing proteins of hair

• Hair finding: tiger tail hair (Q) to alternating light and dark bands under polarized light microscopy

Mnemonic

pibids Syndrome (Trichothiodystrophy features)

P = Photosensitivity | I = Ichthyosis | B = Brittle hair I = Intellectual impairment | D = Decreased fertility | S = Short stature

Image summary: This figure is a photomicrograph. It displays a network of elongated, filamentous structures that overlap and crisscross across the field of view. These filaments exhibit internal segmentation and varying degrees of density in their internal contents. The presence of these long, multicellular thread-like structures indicates a filamentous organism, likely a type of algae or fungi, characterized by a linear growth pattern and a compartmentalized cellular arrangement.

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