Basic Dermatology — MCQs

Basic Dermatology Indian Medical PG Practice Questions and MCQs

Question 361: Darier's disease is associated with:

A. Vitamin A deficiency and night blindness
B. ATP2A2 gene mutation and acantholytic dyskeratosis (Correct Answer)
C. Human papillomavirus infection and wart formation
D. Autoimmune destruction of melanocytes

Explanation: ***ATP2A2 gene mutation and acantholytic dyskeratosis*** - This is the **correct association for Darier's disease** (keratosis follicularis), an autosomal dominant genodermatosis - Caused by mutation in the **ATP2A2 gene** on chromosome 12q23-24.1, which encodes **SERCA2** (calcium ATPase pump in endoplasmic reticulum) - Defective calcium signaling leads to impaired keratinocyte adhesion and differentiation - Results in **acantholytic dyskeratosis** - the hallmark histopathological finding showing abnormal keratinization and loss of cohesion between epidermal cells - **Clinical features:** greasy keratotic papules in seborrheic distribution, palmoplantar pits, nail abnormalities with V-shaped nicking *Autoimmune destruction of melanocytes* - This describes **vitiligo**, not Darier's disease - Vitiligo is characterized by autoimmune destruction of melanocytes leading to depigmented patches - Completely unrelated to the genetic and structural defects seen in Darier's disease *Vitamin A deficiency and night blindness* - **Vitamin A deficiency** causes ocular manifestations including **night blindness (nyctalopia)** and xerophthalmia - Also causes skin changes like **follicular hyperkeratosis (phrynoderma)** - Not associated with Darier's disease, which is a genetic disorder *Human papillomavirus infection and wart formation* - **HPV infection** causes **warts (verrucae)** - benign epithelial proliferations - Results from viral infection of keratinocytes, not genetic calcium pump dysfunction - Unrelated to Darier's disease pathophysiology

Question 362: Palpable purpura could occur in the following conditions, except:

A. Disseminated gonococcal infection
B. Acute meningococcemia
C. Small-vessel vasculitis
D. Thrombocytopenia (Correct Answer)

Explanation: ***Correct: Thrombocytopenia*** - In **pure thrombocytopenia**, bleeding manifests as **petechiae** (pinpoint, non-palpable red spots) and **ecchymoses** (bruises), which are typically **non-palpable** and result from extravasated blood **without inflammation**. - **Palpable purpura** requires inflammation of blood vessels (vasculitis), which is absent in simple platelet deficiency. *Incorrect: Small-vessel vasculitis* - **Palpable purpura** is the **classic hallmark** of small-vessel vasculitis (leukocytoclastic vasculitis). - Results from **immune complex deposition** in vessel walls, leading to inflammatory cell infiltration and palpable lesions. - Conditions like **Henoch-Schönlein purpura** and **hypersensitivity vasculitis** characteristically present with palpable purpura. *Incorrect: Disseminated gonococcal infection* - Can cause **septic vasculitis** with palpable purpuric lesions. - Presents with **papulopustular or hemorrhagic lesions** that may progress from macules/petechiae to palpable purpura. - Lesions are typically few in number and occur on distal extremities. *Incorrect: Acute meningococcemia* - Presents with rapidly progressive rash: **macules → papules → petechiae → purpura**. - Purpuric lesions become **palpable** due to thrombosis and vessel inflammation. - Severe purpura can coalesce into large ecchymoses with necrotic centers.

Question 363: Which of the following is not classified as a primary cutaneous disorder?

A. Lichen planus
B. Ichthyosis
C. Reiter's disease (Correct Answer)
D. Psoriasis

Explanation: ***Reiter's disease*** - **Reiter's disease**, now known as **Reactive Arthritis**, is characterized by a triad of arthritis, urethritis, and conjunctivitis, often triggered by a preceding infection. - While it can involve mucocutaneous lesions (e.g., **circinate balanitis**, **keratoderma blennorrhagicum**), these are secondary manifestations of a systemic inflammatory process rather than a primary disorder originating in the skin itself. *Lichen planus* - **Lichen planus** is a chronic inflammatory disorder that primarily affects the skin, hair, nails, and mucous membranes. - It presents with characteristic **"6 P's"** (pruritic, purple, polygonal, planar papules and plaques), making it a primary cutaneous condition. *Ichthyosis* - **Ichthyosis** refers to a group of genetic skin disorders characterized by abnormally dry, thickened, and scaly skin due to defects in skin barrier function and keratinization. - These are directly classified as primary disorders of the skin's structure and function. *Psoriasis* - **Psoriasis** is a chronic autoimmune disease that primarily affects the skin, leading to rapid skin cell turnover. - It manifests as well-demarcated, erythematous plaques with silvery scales, making it a classic example of a primary cutaneous disorder.

Question 364: Eosinophilic pustular folliculitis is a rare form of folliculitis that is seen with increased frequency in patients with what?

A. ABPA
B. Asthma
C. Leukemia cutis
D. HIV infection (Correct Answer)

Explanation: ***HIV infection*** - Eosinophilic pustular folliculitis, also known as **Ofuji's disease**, is a pruritic skin condition commonly seen in patients with **advanced HIV disease**. - Its exact pathogenesis is unknown, but it is thought to be an immune dysregulation phenomenon related to the **CD4 count decline** seen in HIV. - The condition presents as recurrent crops of sterile, pruritic follicular papules and pustules, particularly on the face, trunk, and extremities. *ABPA* - **Allergic bronchopulmonary aspergillosis (ABPA)** is a hypersensitivity reaction to *Aspergillus* species, primarily affecting the lungs. - It is characterized by **eosinophilia**, but it does not cause eosinophilic pustular folliculitis. - ABPA is associated with asthma and cystic fibrosis. *Asthma* - **Asthma** is a chronic inflammatory disease of the airways, characterized by **bronchial hyperresponsiveness** and reversible airflow obstruction. - While asthma can involve eosinophilic inflammation of the airways, it is not directly associated with eosinophilic pustular folliculitis. *Leukemia cutis* - **Leukemia cutis** refers to the infiltration of the skin by leukemic cells, often presenting as nodules, plaques, or papules. - This condition is a direct manifestation of leukemia and is biologically distinct from eosinophilic pustular folliculitis.

Question 365: Which of the following conditions does not demonstrate the Koebner phenomenon?

A. Lichen sclerosus (Correct Answer)
B. Lichen planus
C. Vitiligo
D. Psoriasis

Explanation: ***Lichen sclerosus*** - This condition is characterized by **white, atrophic plaques**, primarily affecting the anogenital region, and **typically does not exhibit the Koebner phenomenon** or does so only rarely. - While isolated case reports exist, lichen sclerosus is **not classically considered a Koebnerizing disorder** in standard medical teaching. - The pathogenesis involves **autoimmune processes, genetic factors, and local tissue changes**, rather than a consistent direct response to trauma like the classic Koebnerizing disorders. *Lichen planus* - **Lichen planus** is a **classic example** of the **Koebner phenomenon**, where new violaceous papules develop along lines of trauma or scratching. - This isomorphic response to trauma is a **characteristic diagnostic feature**. - Linear arrangement of lesions following trauma is commonly observed. *Vitiligo* - **Vitiligo** is a **well-recognized Koebnerizing disorder**, with new **depigmented patches** appearing at sites of skin injury, friction, or trauma. - The Koebner phenomenon is reported in **20-60% of vitiligo patients** and is an important mechanism for disease spread. - Common sites include areas of belt pressure, watchbands, and surgical scars. *Psoriasis* - **Psoriasis** is the **most classic example** of the Koebner phenomenon, with new **psoriatic plaques** emerging at sites of trauma, surgery, or even sunburn. - First described by Heinrich Koebner in 1876 in a psoriasis patient. - Occurs in approximately **25-50% of psoriasis patients** and is a key diagnostic clue.

Question 366: Itchy, polygonal, violaceous papules are seen in

A. Psoriasis
B. Pemphigus
C. Lichen planus (Correct Answer)
D. Pityriasis rosea

Explanation: ***Lichen planus*** - This condition is clinically characterized by the "6 P's": **pruritic**, **polygonal**, **planar**, **purple**, **papules**, and **plaques**. The description fits perfectly. - Microscopic findings often include a **saw-tooth rete ridge pattern** and a dense lymphocytic infiltrate at the dermoepidermal junction. *Psoriasis* - Characterized by **well-demarcated erythematous plaques** with **silvery scales**, often found on extensor surfaces. - Histologically, it shows **acanthosis** with elongated rete ridges, parakeratosis, and neutrophilic infiltrates (Munro microabscesses). *Pemphigus* - An autoimmune blistering disease characterized by **flaccid bullae** and erosions, often affecting the skin and mucous membranes. - Caused by autoantibodies against **desmogleins**, leading to intraepidermal blistering (acantholysis). *Pityriasis rosea* - Presents with a **herald patch** followed by smaller, oval-shaped, pinkish-red lesions with fine scales, typically in a "Christmas tree" pattern on the trunk. - It is often associated with a preceding viral infection and is generally **self-resolving**.

Question 367: In which of the following conditions is Koebner phenomenon NOT seen?

A. Lichen planus
B. Erythema multiforme
C. Lichen sclerosus
D. Lichen simplex chronicus (Correct Answer)

Explanation: ***Lichen simplex chronicus*** - The **Koebner phenomenon**, or isomorphic response, is the appearance of new skin lesions at sites of trauma; it is **not seen** in lichen simplex chronicus. - Lichen simplex chronicus is characterized by thickened, leathery skin resulting from **chronic scratching or rubbing**, representing a reactive change rather than an isomorphic response to injury. - This is purely a **reactive hyperplasia** due to chronic trauma, not an inflammatory dermatosis with isomorphic response. *Lichen planus* - **Koebner phenomenon is classically positive** in lichen planus, where new papules can erupt along lines of trauma or scratching. - This is one of the **well-established conditions** showing true isomorphic response, highlighting the underlying **inflammatory nature** of the disease. *Lichen sclerosus* - The Koebner phenomenon can be observed in lichen sclerosus, where new lesions may appear in areas subjected to **friction or minor trauma**. - While debated, this contributes to the spread and persistence of the disease, particularly in affected mucocutaneous areas. *Erythema multiforme* - Koebner phenomenon is **not classically seen** in erythema multiforme, as it is an **acute hypersensitivity reaction** rather than a chronic inflammatory dermatosis. - The target lesions develop due to the underlying **immune reaction** (often triggered by HSV or drugs), not from trauma-induced isomorphic response. - However, among the options, **lichen simplex chronicus** is the most definitive answer as a condition resulting purely from chronic mechanical trauma without isomorphic response.

Question 368: Atrophic cigarette paper scars in the skin are classically seen in which condition?

A. Osteogenesis imperfecta
B. Chondrodysplasia
C. Ehlers-Danlos syndrome (Correct Answer)
D. Marfan syndrome

Explanation: ***Ehlers-Danlos syndrome*** - **Atrophic cigarette paper scars** are a classic dermatological feature due to abnormal collagen synthesis, leading to fragile skin that heals poorly. - The skin in Ehlers-Danlos syndrome is often **hyperextensible** and velvety, contributing to the characteristic scarring after even minor trauma. *Osteogenesis imperfecta* - This condition primarily affects **bone formation**, leading to recurrent fractures and **blue sclera**. - While it involves collagen defects (Type I), it does not classically present with atrophic cigarette paper scars. *Chondrodysplasia* - This is a group of genetic disorders that specifically impact **cartilage and bone development**, leading to skeletal deformities. - It does not present with characteristic skin findings like atrophic scarring. *Marfan syndrome* - This genetic disorder primarily affects **connective tissue**, leading to issues in the cardiovascular system (e.g., **aortic dissection**), eyes (e.g., **lens dislocation**), and skeletal system (e.g., **arachnodactyly**). - While it affects connective tissue, **atrophic cigarette paper scars** are not a typical skin manifestation of Marfan syndrome.

Question 369: Which skin lesion is associated with Sturge-Weber syndrome?

A. Port-wine stain (Correct Answer)
B. Strawberry nevus
C. Mongolian spot
D. Salmon patch

Explanation: ***Port-wine stain*** - A **port-wine stain (nevus flammeus)**, especially when located on the face following the trigeminal nerve distribution, is the characteristic skin lesion of **Sturge-Weber syndrome**. - Sturge-Weber syndrome is a **neurocutaneous disorder** associated with neurological abnormalities like seizures, glaucoma, and leptomeningeal angioma. *Salmon patch* - A **salmon patch (nevus simplex)** is a common, benign vascular lesion typically found on the eyelids, glabella, or nape of the neck. - Unlike a port-wine stain, a salmon patch usually **fades within the first year of life** and is not associated with Sturge-Weber syndrome. *Strawberry nevus* - A **strawberry nevus (infantile hemangioma)** is a common benign vascular tumor that typically appears a few weeks after birth, grows rapidly, and then usually regresses spontaneously by age 5-10. - It is a **raised, bright red lesion** that is distinct from the flat, diffuse appearance of a port-wine stain and not directly linked to Sturge-Weber syndrome. *Mongolian spot* - A **Mongolian spot (dermal melanocytosis)** is a benign, flat, bluish-gray pigmented lesion commonly found on the lower back or buttocks of infants, particularly those with darker skin tones. - It results from **melanocytes trapped in the dermis** and typically fades during childhood, having no association with Sturge-Weber syndrome.

Practice by Chapter

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