Basic Dermatology — MCQs

Basic Dermatology Indian Medical PG Practice Questions and MCQs

Question 261: Identify the lesion shown below.

A. Geographic tongue
B. Black hairy tongue
C. Stevens-Johnson syndrome (Correct Answer)
D. Acrodermatitis enteropathica

Explanation: ***Stevens-Johnson syndrome*** - The image shows a child with widespread **erosions and crusted lesions** primarily on the face, including peri-oral and ocular involvement, which is highly characteristic of **Stevens-Johnson syndrome (SJS)**. - SJS is a severe, acute mucocutaneous reaction typically triggered by drugs, characterized by **epidermal detachment** and involvement of at least two mucous membranes. *Geographic tongue* - **Geographic tongue** (benign migratory glossitis) is a benign condition characterized by irregular, erythematous patches on the tongue with white borders due to **loss of filiform papillae**. - It affects only the tongue and does not involve widespread skin and mucosal lesions as seen in the image. *Black hairy tongue* - **Black hairy tongue** is a harmless condition where the papillae on the tongue become elongated and discolored, often due to poor oral hygiene, smoking, or antibiotic use. - It is confined to the dorsum of the tongue and presents as a furry, dark overgrowth, not the erosive and crusted lesions seen in the image. *Acrodermatitis enteropathica* - **Acrodermatitis enteropathica** is a rare, inherited or acquired **zinc deficiency** disorder presenting with a characteristic triad of **dermatitis**, **diarrhea**, and **alopecia**. - The dermatitis typically affects acral and periorificial areas, but the lesions are usually erythematous, vesicular, bullous, or pustular, and classically scaly, rather than the extensive erosions and crusting seen in the image.

Question 262: A 40 year old man with a known case of chronic pancreatitis presents to the OPD with complaint of skin pigmentation over the abdomen. The patient gives a history of chronic use of a hot water bottle to relieve the abdominal discomfort. Which one of the following is the most appropriate diagnosis?

A. Erythema infectiosum
B. Erythema marginatum
C. Erythema ab igne (Correct Answer)
D. Erythema nodosum

Explanation: ***Erythema ab igne*** - This condition is caused by **chronic exposure to moderate heat**, which aligns with the patient's history of using a hot water bottle for abdominal discomfort. - It presents as **reticulated erythema** and **hyperpigmentation** on the affected skin, precisely matching the description of skin pigmentation over the abdomen. *Erythema infectiosum* - This is also known as **Fifth disease** and is caused by **Parvovirus B19**. - It typically presents with a characteristic **"slapped cheek" rash** on the face and a lacy rash on the trunk and limbs, which is not consistent with the patient's presentation. *Erythema marginatum* - This is a rare, transient rash associated with **acute rheumatic fever**. - It presents as **pink-red macules with clear centers and serpiginous borders** that migrate, which does not fit the described chronic pigmentation. *Erythema nodosum* - This condition is characterized by **tender, red nodules** typically found on the **shins**. - It is a form of **panniculitis** (inflammation of subcutaneous fat) and is not caused by chronic heat exposure, nor does it present as diffuse pigmentation.

Question 263: Which of the following are true about epidermal cyst? 1. It is lined by stratified squamous epithelium. 2. It is derived from hair follicle. 3. It contains keratin debris. 4. It is not fixed to the skin.

A. 1, 3 and 4
B. 1, 2 and 4
C. 2, 3 and 4
D. 1, 2 and 3 (Correct Answer)

Explanation: ***1, 2 and 3*** - An **epidermal cyst** is indeed derived from the **infundibulum of a hair follicle**. - It is lined by **stratified squamous epithelium** and contains **keratin debris**, giving it a cheesy consistency. *1, 3 and 4* - While an epidermal cyst is lined by stratified squamous epithelium and contains keratin, it is often **fixed to the skin** due to its attachment to the follicular opening, making statement 4 incorrect. - The cyst's connection to the surface epithelium is a distinguishing feature, preventing it from being freely mobile. *1, 2 and 4* - Although statements 1 and 2 are true, statement 4, claiming it is not fixed to the skin, is generally **incorrect**. - Epidermal cysts typically have a punctum or small opening to the skin surface, indicating its attachment. *2, 3 and 4* - Statements 2 and 3 are correct, but statement 4, suggesting it is not fixed, is **false**. - The presence of a **central punctum**, which is common in epidermal cysts, signifies its epidermal origin and attachment to the skin.

Question 264: A patient presents with orange-hued skin lesions and hyperkeratotic palms and soles. A biopsy shows alternating parakeratosis and orthokeratosis. What is the most likely diagnosis?

A. Pityriasis rubra pilaris (Correct Answer)
B. Follicular psoriasis
C. Keratosis follicularis
D. Ichthyosis vulgaris

Explanation: ***Pityriasis rubra pilaris*** - This condition classically presents with **salmon-colored to orange-hued plaques** and **hyperkeratotic palms and soles**. - Histologically, Pityriasis rubra pilaris is characterized by **alternating parakeratosis and orthokeratosis** in vertical and horizontal directions ("checkerboard" pattern). *Follicular psoriasis* - While psoriasis can present with hyperkeratosis and scales, **follicular psoriasis** specifically involves the hair follicles, seen as follicular papules and pustules. - The classic alternating parakeratosis and orthokeratosis is more indicative of PRP than of follicular psoriasis, which typically shows more uniform parakeratosis. *Keratosis follicularis* - Also known as Darier disease, this condition presents with **greasy, crusted, foul-smelling papules** on seborrheic areas. - Histopathology reveals characteristic **dyskeratosis** with acantholytic cells (corps ronds and grains), which is different from the described alternating parakeratosis and orthokeratosis. *Ichthyosis vulgaris* - This is a genetic disorder characterized by **dry, scaly skin** due to impaired epidermal barrier function, often worse in winter. - Histopathology typically shows a **diminished or absent granular layer** and compact orthokeratosis without parakeratosis, differing from the biopsy findings.

Question 265: A patient's skin biopsy shows a box-shaped or square-shaped pattern of inflammatory infiltrate, as shown in the image. What is the most likely diagnosis?

A. Lichen planus (Correct Answer)
B. Lichen amyloidosis
C. Morphea
D. Lichen nitidus

Explanation: ***Lichen planus*** - The image shows a characteristic **"box-shaped" or "square-shaped" infiltrate** of lymphocytes at the dermal-epidermal junction, obscuring the basal layer. - Other features consistent with lichen planus include **hypergranulosis**, **sawtooth rete ridges**, and **Civatte bodies** (apoptotic keratinocytes) in the basal layer. *Lichen amyloidosis* - This condition is characterized by deposition of **amyloid material** in the papillary dermis, often associated with keratinocyte necrosis. - While it can present with pruritic papules similar to lichen planus, the histology specifically shows **amyloid deposits**, not the typical basal cell damage or band-like infiltrate seen in the image. *Morphea* - Morphea is a form of localized scleroderma, characterized by **thickening of collagen bundles** in the dermis and subcutaneous tissue, leading to hardened skin plaques. - Histologically, it involves **sclerosis** and homogenization of collagen, with a sparse inflammatory infiltrate, which is distinct from the dense band-like infiltrate and epidermal changes shown. *Lichen nitidus* - Lichen nitidus is characterized by **small, discrete granulomas** within the papillary dermis (the "ball-and-claw" appearance), with epithelial extensions embracing the inflammatory infiltrate. - It involves a more **localized inflammatory process** and distinct granulomatous appearance, rather than the broad, band-like infiltrate seen across the dermal-epidermal junction in this image.

Question 266: The skin biopsy shown below is most consistent with which of the following conditions? ![img-28.jpeg](img-28.jpeg)

A. Lichen planus (Correct Answer)
B. Lichen nitidus
C. Morphea
D. Lupus erythematosus

Explanation: ***Lichen planus*** - The image shows **basal cell degeneration** (liquefaction degeneration), a **sawtooth rete ridge pattern**, and a band-like inflammatory infiltrate primarily composed of lymphocytes at the dermo-epidermal junction, which are classic histological features of **lichen planus**. - **Civatte bodies** (apoptotic keratinocytes forming colloid bodies) are typically present, resulting from keratinocyte damage at the basal layer. - These features make lichen planus the most consistent diagnosis. *Lichen nitidus* - Characterized by **"ball and claw" lesions**, which are small, localized epidermal invaginations enclosing a central infiltrate of lymphocytes and histiocytes. - The granulomatous infiltrate is more focal and circumscribed compared to the band-like pattern of lichen planus. - While both are interface dermatitides, the architectural pattern differs significantly. *Morphea* - This is a localized form of **scleroderma**, characterized by increased **collagen deposition**, thickening of the dermis, and loss of adnexal structures like hair follicles and sweat glands. - The inflammatory infiltrate is typically perivascular and interstitial, not band-like at the dermo-epidermal junction. - The image does not show features of dermal fibrosis or homogenization of collagen bundles expected in morphea. *Lupus erythematosus* - Also shows **interface dermatitis** with basal vacuolar changes and lymphocytic infiltrate. - However, lupus typically shows a **perivascular and periappendageal pattern** of infiltrate rather than the dense band-like pattern of lichen planus. - Additional features in lupus include dermal mucin deposition, thickened basement membrane (PAS-positive), and follicular plugging. - The dense, continuous band-like infiltrate and sawtooth rete ridges favor lichen planus over lupus.

Question 267: A patient who has always neglected his nutrition presented with follicular hyperkeratosis on the extensor aspect of the forearm. What is the diagnosis?

A. Phrynoderma (Correct Answer)
B. Eruptive xanthoma
C. Darier's disease
D. Folliculitis

Explanation: ***Phrynoderma*** - **Phrynoderma**, also known as **toad skin**, is characterized by **follicular hyperkeratosis**, particularly on the **extensor surfaces** of limbs like the forearm. - This condition is closely linked to **nutritional deficiencies**, often involving **vitamin A**, **essential fatty acids**, or sometimes **B vitamins**. *Eruptive xanthoma* - **Eruptive xanthomas** are small, yellow-red papules that often appear suddenly, typically on the **buttocks**, **extensor surfaces of the limbs**, and **trunk**. - They are a cutaneous manifestation of **severe hypertriglyceridemia** and not primarily related to general nutritional neglect or follicular hyperkeratosis. *Darier's disease* - **Darier's disease** is a **rare, inherited genetic disorder** characterized by greasy, crusted papules primarily in **seborrheic areas** such as the scalp, forehead, chest, and groin. - It results from a mutation in the **ATP2A2 gene**, affecting calcium signaling in keratinocytes, and is not a nutritional deficiency condition. *Folliculitis* - **Folliculitis** is the inflammation of one or more **hair follicles**, often caused by **bacterial** (e.g., *Staphylococcus aureus*) or **fungal infections**. - It presents as small, red, sometimes pus-filled bumps around hair follicles, distinct from the dry, rough texture of follicular hyperkeratosis seen in phrynoderma.

Question 268: A young girl presents to the outpatient department with rough-surfaced lesions over her elbows and knees. She also complains of diminished vision at night. What is the most likely diagnosis?

A. Folliculitis
B. Pyoderma
C. Keratosis pilaris
D. Phrynoderma (Correct Answer)

Explanation: ***Phrynoderma*** - Phrynoderma, also known as **follicular hyperkeratosis**, presents with **rough, horny papules** over extensor surfaces like elbows and knees, often described as "toad skin." - It is a skin manifestation of **vitamin A deficiency**, which also causes **night blindness** (nyctalopia) due to impaired production of rhodopsin. *Folliculitis* - This is an **inflammation of hair follicles**, appearing as small, red bumps or pustules centered around hair follicles. - It is typically caused by bacterial or fungal infections and does not cause **night blindness**. *Pyoderma* - **Pyoderma** refers to a **pus-producing skin infection** caused by bacteria, such as impetigo or cellulitis. - These are characterized by crusts, blisters, or inflamed lesions and are not associated with **rough skin** or **night blindness**. *Keratosis pilaris* - This common genetic condition causes small, rough bumps, typically on the upper arms, thighs, and buttocks, due to **keratin plugging hair follicles**. - While it causes rough skin similar to phrynoderma, it is generally **benign** and does not cause systemic symptoms like **night blindness**.

Question 269: Match the following scale types with their lesions. | Scales | Lesions | | :-- | :-- | | 1. Collarette scales | a. Pityriasis versicolour | | 2. Silvery scales | b. Pityriasis rosea | | 3. Mica-like scales | c. Psoriasis | | 4. Branny scales | d. Pityriasis lichenoides |

A. 1-d, 2-c, 3-a, 4-b
B. 1-c, 2-b, 3-d, 4-a
C. 1-a, 2-b, 3-d, 4-c
D. 1-b, 2-c, 3-d, 4-a (Correct Answer)

Explanation: ***1-b, 2-c, 3-d, 4-a*** - **Collarette scales** are pathognomonic of **Pityriasis rosea**, appearing as fine, trailing scales around the periphery of oval lesions in a "Christmas tree" distribution. - **Silvery scales** are the classic hallmark of **Psoriasis**, presenting as thick, adherent, silvery-white scales overlying well-demarcated erythematous plaques. - **Mica-like scales** are characteristic of **Pityriasis lichenoides**, appearing as thick, shiny, adherent scales that can be peeled off like mica sheets. - **Branny scales** are typical of **Pityriasis versicolor**, presenting as fine, powdery scales caused by **Malassezia** yeast overgrowth. *1-d, 2-c, 3-a, 4-b* - Incorrectly matches **collarette scales with Pityriasis lichenoides**, which typically presents with mica-like scales, not collarette scales. - Misassociates **mica-like scales with Pityriasis versicolor**, which characteristically has branny (fine, powdery) scales. *1-c, 2-b, 3-d, 4-a* - Wrongly pairs **collarette scales with Psoriasis**, which is known for thick silvery scales, not peripheral collarette scales. - Incorrectly matches **silvery scales with Pityriasis rosea**, which has collarette scales at lesion periphery, not silvery scales. *1-a, 2-b, 3-d, 4-c* - Falsely associates **collarette scales with Pityriasis versicolor**, which has branny scales from yeast infection, not collarette scales. - Mismatches **branny scales with Psoriasis**, which has characteristic thick silvery scales, not fine powdery scales.

Question 270: A 24-year-old male presents with asymptomatic scaly lesions over the body as shown in the image below. What is the likely diagnosis?

A. Atopic Dermatitis
B. Lichen planus
C. Seborrheic Dermatitis
D. Pityriasis Rosea (Correct Answer)

Explanation: ***Pityriasis Rosea*** - The image shows numerous **scaly, erythematous plaques** distributed over the trunk, with a characteristic "Christmas tree" pattern often observed in Pityriasis Rosea. - The lesions are described as **asymptomatic**, which is consistent with Pityriasis Rosea, although mild pruritus can occur. *Atopic Dermatitis* - Typically presents with **intensely pruritic, erythematous, and eczematous lesions** often found in flexural areas (e.g., antecubital and popliteal fossae). - While it can be widespread, the morphology of the lesions (eczematous vs. scaly plaques) and the absence of pruritus make this less likely. *Lichen planus* - Characterized by **pruritic, violaceous, polygonal papules** and plaques, often appearing on the flexor surfaces of wrists, ankles, and oral mucosa. - The appearance of the lesions in the image does not match the typical morphology of lichen planus. *Seborrheic Dermatitis* - Primarily affects areas with a high density of sebaceous glands, such as the **scalp, face (nasolabial folds, eyebrows), and chest**. - Presents with **greasy, yellowish scales** on an erythematous base, which is distinct from the dry, scaly plaques seen in the image.

Practice by Chapter

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Cutaneous Immunology

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