Basic Dermatology — MCQs

Basic Dermatology Indian Medical PG Practice Questions and MCQs

Question 81: What is the recommended treatment for pyoderma gangrenosum?

A. Corticosteroids
B. Intravenous antibiotics
C. Surgery combined with antibiotics (Correct Answer)
D. Surgery alone

Explanation: **Explanation:** Pyoderma gangrenosum (PG) is a rare, non-infectious inflammatory neutrophilic dermatosis. While the name suggests an infectious etiology, it is actually an **autoinflammatory condition** often associated with systemic diseases like Inflammatory Bowel Disease (IBD), rheumatoid arthritis, or hematologic malignancies. **Why Option C is Correct:** In the context of this specific question, the management of PG focuses on controlling the underlying inflammatory process while preventing secondary infection. While **systemic corticosteroids** are traditionally the first-line medical treatment, clinical management often necessitates a multidisciplinary approach. **Surgery combined with antibiotics** (Option C) is indicated when there is extensive tissue necrosis or secondary bacterial superinfection. However, it is critical to note that surgery must be performed under the cover of immunosuppression/antibiotics to prevent **pathergy**. **Why Other Options are Incorrect:** * **Option A (Corticosteroids):** While these are the mainstay of medical therapy, the question identifies Option C as the preferred answer, likely emphasizing the management of complicated or infected cases. * **Option B (Intravenous antibiotics):** PG is not primarily an infectious process; antibiotics alone will not treat the underlying neutrophilic infiltration. * **Option D (Surgery alone):** This is **contraindicated**. Surgery alone triggers the phenomenon of **pathergy**, where minor trauma (including surgical debridement) causes the ulcer to rapidly expand and worsen. **NEET-PG High-Yield Pearls:** 1. **Pathergy Phenomenon:** Development of new lesions or worsening of existing ones at the site of even minor trauma (also seen in Behcet’s disease and Sweet syndrome). 2. **Clinical Presentation:** Painful, rapidly evolving ulcer with a **violaceous (purple), undermined border**. 3. **Histopathology:** Shows a dense dermal neutrophilic infiltrate (sterile abscess). 4. **First-line Medical Treatment:** Systemic Corticosteroids (Cyclosporine is a common second-line agent).

Question 82: Which one of the following is not a lichenoid reaction?

A. Lichenoid contact reaction
B. Pemphigus (Correct Answer)
C. Lichenoid drug eruption
D. Lichenoid reaction of graft versus host disease

Explanation: **Explanation:** The term **Lichenoid Reaction** refers to a specific histopathological pattern characterized by **interface dermatitis**. The hallmark of this reaction is a dense, band-like infiltrate of lymphocytes at the dermo-epidermal junction, leading to "liquefaction degeneration" (vacuolar degeneration) of the basal layer of the epidermis. **Why Pemphigus is the correct answer:** Pemphigus (such as Pemphigus Vulgaris) is an **autoimmune bullous disorder** caused by antibodies against desmogleins (cell-to-cell adhesion molecules). Its primary pathology is **acantholysis** (loss of intercellular connections) leading to intraepidermal blisters. It does not involve an interface lymphocytic reaction or basal layer degeneration; therefore, it is not a lichenoid reaction. **Analysis of Incorrect Options:** * **Lichenoid Contact Reaction:** This is a localized T-cell mediated delayed hypersensitivity reaction (Type IV) occurring at the site of contact with certain substances (e.g., dental amalgam), mimicking lichen planus histologically. * **Lichenoid Drug Eruption:** Many drugs (e.g., Beta-blockers, NSAIDs, Antimalarials) can trigger a "lichen planus-like" eruption. Histology shows the classic band-like infiltrate, often with eosinophils. * **Lichenoid Graft vs. Host Disease (GVHD):** Chronic GVHD frequently presents with lichenoid papules and plaques. The pathology shows a classic interface dermatitis as the donor T-cells attack the host's basal keratinocytes. **High-Yield Clinical Pearls for NEET-PG:** * **Civatte Bodies (Colloid Bodies):** These are apoptotic keratinocytes found in the lower epidermis/upper dermis in lichenoid reactions. * **Max Joseph Spaces:** Small areas of separation between the epidermis and dermis due to extensive basal cell degeneration in Lichen Planus. * **Wickham Striae:** The clinical white reticular lines seen in Lichen Planus, caused by focal orthokeratosis and wedge-shaped hypergranulosis.

Question 83: Erythema multiforme is:

A. An acute, self-limiting disease of the skin and oral mucous membrane (Correct Answer)
B. A painless, vesicular, self-limiting disease
C. A viral disease
D. A bacterial infection

Explanation: **Explanation:** **Erythema Multiforme (EM)** is an acute, immune-mediated mucocutaneous condition characterized by the sudden appearance of symmetric, erythematous skin lesions. It is considered **self-limiting**, typically resolving within 2 to 4 weeks. It frequently involves the **oral mucous membranes** (in about 70% of cases), presenting as painful erosions and ulcerations. The hallmark lesion is the **"target" or "iris" lesion**, consisting of three concentric zones: a dusky central disk (sometimes with a vesicle), a pale edematous ring, and an erythematous halo. **Analysis of Options:** * **Option A (Correct):** Accurately describes the clinical course (acute and self-limiting) and the primary sites of involvement (skin and oral mucosa). * **Option B (Incorrect):** While EM can be vesicular (EM Major), it is **not painless**. Mucosal involvement is typically very painful, leading to difficulty in eating and drinking. * **Option C (Incorrect):** EM is not a viral disease itself; it is a **Type IV hypersensitivity reaction**. While it is most commonly *triggered* by a virus (Herpes Simplex Virus), the pathology is immunological, not a direct viral infection of the skin. * **Option D (Incorrect):** It is not a bacterial infection, though *Mycoplasma pneumoniae* is a known precipitating factor. **High-Yield Clinical Pearls for NEET-PG:** * **Most common trigger:** Herpes Simplex Virus (HSV-1 and HSV-2) is responsible for >90% of cases. * **EM Minor:** Minimal or no mucosal involvement; symmetric target lesions on extremities. * **EM Major:** Significant mucosal involvement (at least two sites, usually oral) with systemic symptoms like fever. * **Histology:** Shows vacuolar degeneration of the basal layer and keratinocyte necrosis (satellite cell necrosis). * **Distinction:** EM is now considered distinct from Stevens-Johnson Syndrome (SJS), which is primarily drug-induced.

Question 84: Which of the following is NOT a primary skin disease?

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

Explanation: **Explanation:** The distinction between primary skin diseases and multisystemic syndromes is a high-yield concept in dermatology. **Why Reiter’s Disease is the Correct Answer:** Reiter’s disease (now more commonly referred to as **Reactive Arthritis**) is a multisystemic, immune-mediated condition that typically follows a gastrointestinal or genitourinary infection. It is defined by the classic clinical triad: **Urethritis, Conjunctivitis, and Arthritis** ("Can't see, can't pee, can't climb a tree"). While it has prominent cutaneous manifestations—such as *Keratoderma blennorrhagicum* and *Circinate balanitis*—the disease itself is a systemic inflammatory syndrome, not a primary disorder of the skin. **Analysis of Incorrect Options:** * **Lichen Planus (A):** A primary inflammatory skin disease characterized by the "6 Ps" (Planar, Purple, Polygonal, Pruritic, Papules, and Plaques). It primarily affects the skin, mucous membranes, hair, and nails. * **Psoriasis (B):** A chronic, primary T-cell-mediated autoimmune skin disorder characterized by well-demarcated erythematous plaques with silvery scales. * **Vitiligo (C):** A primary pigmentary disorder of the skin caused by the autoimmune destruction of melanocytes, leading to depigmented macules and patches. **High-Yield Clinical Pearls for NEET-PG:** * **Keratoderma blennorrhagicum:** These are vesicopustular, waxy lesions on the palms and soles, pathognomonic for Reiter’s disease; histologically, they are indistinguishable from pustular psoriasis. * **HLA Association:** Reiter’s disease is strongly associated with **HLA-B27**. * **Koebner Phenomenon:** Remember that both Psoriasis and Lichen Planus exhibit the Koebner phenomenon (isomorphic response).

Question 85: Regarding Erythema multiforme, all are true except?

A. Absence of vesicles (Correct Answer)
B. Presence of target lesions
C. Involvement of face and neck regions
D. Sign of internal malignancy

Explanation: **Explanation:** **Erythema Multiforme (EM)** is an acute, self-limiting Type IV hypersensitivity reaction. The correct answer is **A** because the statement "Absence of vesicles" is false. In EM, the characteristic "target" or "iris" lesion often features a central zone that can become **vesicular, bullous, or necrotic**. Therefore, vesicles are a common clinical finding in the center of the lesions. **Analysis of Options:** * **Option B (Target lesions):** This is the hallmark of EM. A classic target lesion consists of three concentric zones: a dusky/vesicular center, a pale edematous ring, and an erythematous outer halo. * **Option C (Face and neck involvement):** EM typically has a symmetrical acral distribution, frequently involving the face, neck, and distal extremities (palms and soles). * **Option D (Sign of internal malignancy):** While most cases are triggered by infections (HSV being the most common), EM can occasionally occur as a paraneoplastic phenomenon associated with underlying internal malignancies (e.g., carcinomas or lymphomas). **High-Yield Clinical Pearls for NEET-PG:** * **Most Common Trigger:** Herpes Simplex Virus (HSV-1 and HSV-2) is the most frequent cause of EM Minor. *Mycoplasma pneumoniae* is the most common bacterial cause (often associated with EM Major). * **EM Minor vs. Major:** EM Minor involves little to no mucosal involvement; EM Major involves at least two mucosal surfaces (oral, ocular, or genital). * **Differential Diagnosis:** Unlike Stevens-Johnson Syndrome (SJS), EM is usually triggered by infections rather than drugs and involves <10% body surface area. * **Histology:** Shows vacuolar degeneration of the basal layer and subepidermal bullae.

Question 86: Clutch claw and ball appearance is seen in which of the following conditions?

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

Explanation: **Explanation:** The **"Clutch Claw and Ball"** appearance is a classic histopathological hallmark of **Lichen Nitidus**. This appearance is created by a dense, well-circumscribed lymphohistiocytic infiltrate (the "ball") located within a single dermal papilla, which is closely embraced by elongated, downward-extending epidermal rete ridges (the "clutching claw"). **Why the other options are incorrect:** * **Pemphigus:** Characterized by intraepidermal blisters due to acantholysis (loss of intercellular connections). Histology shows a "row of tombstones" appearance on the basal layer. * **Lichen Planus:** Features a "saw-tooth" appearance of rete ridges and a band-like (lichenoid) infiltrate at the dermo-epidermal junction, but lacks the focal "ball" configuration. * **Psoriasis:** Notable for regular elongation of rete ridges (test-tube appearance), Munro’s microabscesses, and Kogoj’s pustules, but does not show the claw and ball pattern. **High-Yield Clinical Pearls for NEET-PG:** * **Clinical Presentation:** Lichen Nitidus presents as multiple, tiny (1-2 mm), skin-colored, shiny, flat-topped papules. * **Koebner Phenomenon:** Like Lichen Planus and Psoriasis, Lichen Nitidus can exhibit the Koebner phenomenon (lesions appearing at sites of trauma). * **Key Histology Buzzword:** "Claw and Ball" or "Ball and Claw" is pathognomonic. * **Common Site:** Often involves the shaft of the penis, forearms, and dorsum of the hands.

Question 87: Which of the following statements regarding lichen planus is false?

A. It presents with pruritic lesions.
B. It can involve the nails.
C. It can involve mucous membranes.
D. Corticosteroids are not used in its treatment. (Correct Answer)

Explanation: **Explanation:** Lichen Planus (LP) is a chronic, inflammatory, T-cell mediated autoimmune condition. The statement **"Corticosteroids are not used in its treatment" is false** because corticosteroids are, in fact, the **first-line treatment** for LP. Topical steroids (e.g., Clobetasol) are used for localized lesions, while systemic steroids are indicated for severe, generalized, or rapidly progressing cases to suppress the immune-mediated destruction of keratinocytes. **Analysis of other options:** * **Option A (Pruritic lesions):** This is a hallmark feature. LP is classically described by the **6 P's**: Planar (flat-topped), Purple, Polygonal, Pruritic, Papules, and Plaques. The itching is often intense. * **Option B (Nail involvement):** Occurs in about 10% of cases. Characteristic findings include longitudinal ridging, splitting, and the pathognomonic **Pterygium formation** (V-shaped extension of the proximal nail fold onto the nail bed). * **Option C (Mucous membranes):** Frequently involved (Oral LP). It often presents as **Wickham striae** (a white, reticulate, lace-like pattern), most commonly on the buccal mucosa. **NEET-PG High-Yield Pearls:** * **Histopathology:** Shows "saw-tooth" appearance of rete ridges, Civatte bodies (apoptotic keratinocytes), and a band-like lymphocytic infiltrate at the dermo-epidermal junction. * **Koebner Phenomenon:** Development of lesions at sites of trauma (also seen in Psoriasis and Vitiligo). * **Associations:** Strongly associated with **Hepatitis C virus** infection. * **Grinspan’s Syndrome:** Triad of Oral Lichen Planus, Hypertension, and Diabetes Mellitus.

Question 88: Which of the following conditions is characterized by red fluorescent fluid?

A. Pamphigus
B. Erythema multiforme
C. Lichen Planus
D. Porphyria (Correct Answer)

Explanation: **Explanation:** The correct answer is **Porphyria**. This condition is a group of metabolic disorders caused by deficiencies in the enzymes involved in heme biosynthesis, leading to the accumulation of **porphyrins**. Porphyrins are unique chemical compounds that possess a cyclic ring structure capable of absorbing light. When exposed to **Wood’s lamp (365 nm)**, porphyrins in the urine, stool, or blister fluid emit a characteristic **coral-red or pink fluorescence**. This is a classic diagnostic sign, particularly in Porphyria Cutanea Tarda (PCT), where the urine may also appear "tea-colored" or "port-wine" colored under natural light. **Why the other options are incorrect:** * **Pemphigus:** This is an autoimmune bullous disorder characterized by acantholysis (loss of cell-to-cell adhesion). Diagnosis is confirmed via Tzanck smear (acantholytic cells) and Direct Immunofluorescence (DIF) showing a "fish-net" pattern, but the blister fluid itself does not fluoresce. * **Erythema Multiforme:** A hypersensitivity reaction (often triggered by HSV). It presents with "target lesions." Diagnosis is clinical or histological; it does not involve porphyrin metabolism. * **Lichen Planus:** An inflammatory condition characterized by the "6 Ps" (Pruritic, Polygonal, Purple, Planar, Papules, and Plaques). While it may show Wickham striae, it lacks any fluorescent fluid properties. **NEET-PG High-Yield Pearls:** * **Wood’s Lamp Findings:** * *Erythrasma:* Coral-red (due to Coproporphyrin III). * *Tinea versicolor:* Yellowish-white/Golden yellow. * *Pseudomonas:* Apple green. * *Vitiligo:* Milky white. * **Porphyria Cutanea Tarda (PCT):** The most common porphyria; associated with Hepatitis C, alcohol, and iron overload. It presents with skin fragility and subepidermal blisters on sun-exposed areas.

Question 89: Ichthyosis is associated with which of the following conditions?

A. Hodgkin's disease
B. AIDS
C. Hypothyroidism
D. All of the above (Correct Answer)

Explanation: **Explanation:** The question refers to **Acquired Ichthyosis**, a non-hereditary skin disorder characterized by symmetric, fish-like scaling. Unlike hereditary forms (like Ichthyosis Vulgaris), acquired ichthyosis appears in adulthood and serves as a crucial cutaneous marker for systemic disease. **Why "All of the above" is correct:** Acquired ichthyosis is strongly associated with internal malignancies, infections, and metabolic derangements: * **Hodgkin’s Disease:** This is the most common malignancy associated with acquired ichthyosis. It often presents as a paraneoplastic syndrome, sometimes appearing months or years before the lymphoma is diagnosed. * **AIDS:** HIV infection can trigger severe xerosis and ichthyosiform changes due to altered lipid metabolism in the skin and immune dysregulation. * **Hypothyroidism:** Thyroid hormones are essential for epidermal cholesterol synthesis and barrier function. Hypothyroidism leads to decreased sebum production and "dry, cold skin," which can manifest as acquired ichthyosis. **Clinical Pearls for NEET-PG:** 1. **Paraneoplastic Marker:** If a patient develops ichthyosis for the first time in adulthood, the first priority is to rule out occult malignancy, specifically **Hodgkin’s Lymphoma**. 2. **Drug-induced Ichthyosis:** High-yield drugs causing this include **clofazimine**, nicotinic acid, and cholesterol-lowering agents (statins). 3. **Histology:** Similar to Ichthyosis Vulgaris, it shows hyperkeratosis and a **reduced or absent granular layer**. 4. **Sarcoidosis:** Another high-yield systemic association often tested in exams. **Summary:** Because acquired ichthyosis is a multi-etiological sign of systemic pathology, it can be triggered by malignancies (Hodgkin's), chronic infections (AIDS), and endocrine disorders (Hypothyroidism).

Question 90: What is the classical presentation described?

A. Pityriasis Rosea (Correct Answer)
B. Pityriasis Alba
C. Pityriasis Rubra
D. Pityriasis Versicolor

Explanation: ***Pityriasis Rosea*** - Classical presentation includes a **herald patch** (initial large oval lesion) followed by smaller **salmon-colored oval lesions** distributed in a **Christmas tree pattern** on the trunk. - Lesions follow **Langer's lines** and typically appear on the **trunk and proximal extremities**, often with mild **pruritus**. *Pityriasis Alba* - Presents as **hypopigmented patches** with fine **scaling**, commonly on the **face and arms** of children. - Associated with **atopic dermatitis** and lacks the characteristic **herald patch** and Christmas tree distribution. *Pityriasis Rubra* - Also known as **pityriasis rubra pilaris**, characterized by **orange-red scaly plaques** with **islands of normal skin**. - Presents with **keratoderma** of palms and soles, and **follicular hyperkeratosis**, unlike the oval lesions of pityriasis rosea. *Pityriasis Versicolor* - Caused by **Malassezia furfur** fungus, presenting as **hypo- or hyperpigmented patches** with fine scaling. - Typically affects **seborrheic areas** like chest, back, and shoulders, with **positive KOH test** showing spaghetti and meatballs appearance.

Practice by Chapter

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