Basic Dermatology Practice Questions

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

Pemphigus. **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.

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

Reiter's disease. **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).

Q: Regarding Erythema multiforme, all are true except?

Absence of vesicles. **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.

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

Lichen nitidus. **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.

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

Corticosteroids are not used in its treatment.. **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.

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

Porphyria. **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.

Q: Ichthyosis is associated with which of the following conditions?

All of the above. **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).

Q: What is the classical presentation described?

Pityriasis Rosea. ***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.

Question 1

What is the recommended treatment for pyoderma gangrenosum?

Accepted Answer

Surgery combined with antibiotics

Answer

Corticosteroids

Answer

Intravenous antibiotics

Answer

Surgery alone

Question 2

Which one of the following is not a lichenoid reaction?

Accepted Answer

Pemphigus

Answer

Lichenoid contact reaction

Answer

Lichenoid drug eruption

Answer

Lichenoid reaction of graft versus host disease

Question 3

Erythema multiforme is:

Accepted Answer

An acute, self-limiting disease of the skin and oral mucous membrane

Answer

A painless, vesicular, self-limiting disease

Answer

A viral disease

Answer

A bacterial infection

Question 4

Which of the following is NOT a primary skin disease?

Accepted Answer

Reiter's disease

Answer

Lichen planus

Answer

Psoriasis

Answer

Vitiligo

Question 5

Regarding Erythema multiforme, all are true except?

Accepted Answer

Absence of vesicles

Answer

Presence of target lesions

Answer

Involvement of face and neck regions

Answer

Sign of internal malignancy

Question 6

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

Accepted Answer

Lichen nitidus

Answer

Pemphigus

Answer

Lichen planus

Answer

Psoriasis

Question 7

Which of the following statements regarding lichen planus is false?

Accepted Answer

Corticosteroids are not used in its treatment.

Answer

It presents with pruritic lesions.

Answer

It can involve the nails.

Answer

It can involve mucous membranes.

Question 8

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

Accepted Answer

Porphyria

Answer

Pamphigus

Answer

Erythema multiforme

Answer

Lichen Planus

Question 9

Ichthyosis is associated with which of the following conditions?

Accepted Answer

All of the above

Answer

Hodgkin's disease

Answer

AIDS

Answer

Hypothyroidism

Question 10

What is the classical presentation described?

Accepted Answer

Pityriasis Rosea

Answer

Pityriasis Alba

Answer

Pityriasis Rubra

Answer

Pityriasis Versicolor

Basic Dermatology — MCQs

Basic Dermatology — MCQs

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