Autoimmune Skin Diseases Practice Questions

Q: Gottron's papules are a characteristic clinical finding in which of the following conditions?

Dermatomyositis. **Explanation:** **Dermatomyositis** is the correct answer. Gottron’s papules are considered a **pathognomonic** cutaneous feature of this idiopathic inflammatory myopathy. They are characterized by erythematous to violaceous, flat-topped papules and plaques found symmetrically over the dorsal aspects of the interphalangeal (IP) and metacarpophalangeal (MCP) joints. Pathologically, they represent interface dermatitis similar to lupus but are specific to the bony prominences of the hands. **Why other options are incorrect:** * **Sarcoidosis:** Typically presents with "apple-jelly" nodules, lupus pernio (violaceous plaques on the nose/cheeks), or erythema nodosum. It does not feature Gottron’s papules. * **Scleroderma:** Characterized by skin tightening (sclerodactyly), Raynaud’s phenomenon, and "beaked nose" appearance. While it affects the hands, the pathology involves fibrosis rather than inflammatory papules over joints. * **Fungal infection:** Dermatophytosis (Tinea) usually presents as annular erythematous plaques with central clearing and peripheral scaling, not localized papules over small joints. **NEET-PG High-Yield Pearls:** 1. **Gottron’s Sign:** Symmetrical violaceous erythema (macular) over the knuckles, elbows, or knees (distinguish from *papules*). 2. **Heliotrope Rash:** Violaceous edema of the upper eyelids; another pathognomonic sign. 3. **Shawl Sign & V-Sign:** Photosensitive erythema over the upper back and chest, respectively. 4. **Mechanic’s Hands:** Hyperkeratosis and fissuring of the palms and lateral fingers (associated with **Anti-Jo-1** antibodies and interstitial lung disease). 5. **Malignancy:** Dermatomyositis in adults is frequently associated with internal malignancies (paraneoplastic syndrome).

Q: Salt and pepper dyschromatosis is seen in which of the following conditions?

Scleroderma. **Explanation:** **Salt and pepper dyschromatosis** is a classic clinical sign of **Systemic Sclerosis (Scleroderma)**. It refers to a pattern of diffuse skin pigmentation characterized by areas of **perifollicular sparing** (retained pigment around hair follicles) against a background of depigmentation (leukoderma). The underlying medical concept involves the destruction of melanocytes in the interfollicular epidermis, while the melanocytes within the hair follicle bulbs are preserved. Because hair follicles have a rich capillary network, they are relatively spared from the ischemic changes seen in scleroderma, allowing them to serve as a reservoir for pigment. This sign is often one of the earliest cutaneous markers of the disease, typically appearing on the upper chest, neck, and back. **Analysis of Incorrect Options:** * **Dermatofibrositis:** This is not a standard dermatological term; however, Dermatofibrosarcoma Protuberans (DFSP) presents as a firm, multinodular plaque, not dyschromatosis. * **Systemic Lupus Erythematosus (SLE):** While SLE can cause various pigmentary changes (like post-inflammatory hyperpigmentation or discoid scars), it does not typically manifest with the specific perifollicular sparing seen in the "salt and pepper" pattern. * **Psoriasis:** Characterized by well-demarcated erythematous plaques with silvery-white scales. While it may leave post-inflammatory hypopigmentation, it lacks the specific follicular sparing of scleroderma. **NEET-PG High-Yield Pearls:** * **Salt and Pepper Pigmentation:** Also known as "Scleroderma-associated leukoderma." * **Other Scleroderma Signs:** Microstomia (small mouth), Mouse facies, Raynaud’s phenomenon (earliest symptom), and Sclerodactyly. * **Antibody Association:** Anti-Scl-70 (Diffuse type) and Anti-centromere (Limited/CREST syndrome).

Q: Which of the following drugs is not associated with drug-induced pemphigus?

Furosemide. **Explanation:** Drug-induced pemphigus is a rare but high-yield clinical entity in dermatology. It is primarily triggered by drugs containing a **sulfhydryl (-SH) group** or those that can metabolize into them. **Why Furosemide is the Correct Answer:** Furosemide is a sulfonamide derivative, not a sulfhydryl drug. While it is classically associated with **Drug-induced Bullous Pemphigoid (BP)** and Pseudoporphyria, it is not a recognized trigger for Pemphigus. In BP, the pathology is subepidermal, whereas in Pemphigus, it is intraepidermal (acantholysis). **Analysis of Incorrect Options:** * **Captopril:** This is the classic "prototype" drug for induced pemphigus. It contains a reactive **sulfhydryl group** that directly interferes with desmosomal adhesion (biochemical acantholysis). * **Penicillin:** Along with its derivatives (like Ampicillin), Penicillin is a common non-thiol trigger. It is thought to induce an immune response that leads to the formation of acantholytic antibodies. * **Rifampicin:** This is a well-documented non-thiol trigger for pemphigus. It is believed to act by modulating the immune system or directly affecting keratinocyte adhesion. **NEET-PG High-Yield Pearls:** 1. **Thiol Drugs (Most Common):** Captopril, Penicillamine, Enalapril. These cause direct biochemical acantholysis even without antibody formation. 2. **Non-Thiol Drugs:** Penicillins, Cephalosporins, Rifampicin, Piroxicam, and Phenobarbital. 3. **Clinical Tip:** Drug-induced pemphigus often presents as **Pemphigus Erythematosus** or **Pemphigus Foliaceus** (superficial) rather than Pemphigus Vulgaris. 4. **Prognosis:** Thiol-induced pemphigus often resolves spontaneously upon drug withdrawal (~50% cases), whereas non-thiol induced cases often require systemic steroids.

Q: A 25-year-old man complains of eruptions of blisters on his scalp, inner surface of the groin, and in his mouth. The blisters rupture easily and leave large crusted areas. Histologically, the lesions show separation of the stratum spinosum from the basal layer. The results of direct immunofluorescence microscopy for IgG are shown. Which of the following proteins is targeted by IgG autoantibody in the skin of this patient?

Desmoglein-3. ***Desmoglein-3*** - The clinical presentation of **mucocutaneous blisters** that rupture easily, combined with **suprabasal acantholysis** (separation above the basal layer), is characteristic of **pemphigus vulgaris**. - **Desmoglein-3** is the primary target antigen in pemphigus vulgaris, leading to loss of **intercellular adhesion** and the characteristic **fishnet pattern** on direct immunofluorescence. *Collagen type IV* - **Collagen type IV** is a component of the **basement membrane** and is targeted in **epidermolysis bullosa acquisita**, not pemphigus vulgaris. - This condition shows **subepidermal blistering** with **linear IgG deposition** along the basement membrane, not the intercellular pattern seen here. *E-cadherin* - **E-cadherin** is involved in **cell-cell adhesion** but is not the primary target in autoimmune blistering diseases. - Loss of E-cadherin is associated with **cancer metastasis** and **epithelial-mesenchymal transition**, not autoimmune blistering disorders. *Fibronectin* - **Fibronectin** is an **extracellular matrix protein** involved in **wound healing** and **cell migration**, not targeted by autoantibodies in blistering diseases. - It plays a role in **tissue repair** and **hemostasis** but is not associated with the pathogenesis of pemphigus vulgaris.

Q: Grinspan syndrome is associated with which of the following conditions?

Hypertension, diabetes, lichen planus. ### Explanation **Grinspan Syndrome** is a clinical triad characterized by the coexistence of three specific conditions: **Lichen Planus (usually oral), Diabetes Mellitus, and Hypertension.** The correct answer is **A** because this syndrome was first described by David Grinspan in 1963. While the exact pathophysiology remains debated, many experts believe it is not a unique genetic entity but rather a **medication-induced phenomenon**. Drugs used to treat hypertension (like ACE inhibitors or Beta-blockers) and diabetes (like oral hypoglycemics) are known to trigger **lichenoid drug eruptions** in the oral mucosa, which clinically mimic idiopathic oral lichen planus. #### Analysis of Incorrect Options: * **Option B (Oral, ocular, genital lesions):** This triad is characteristic of **Behçet’s disease**, a systemic vasculitis, not Grinspan syndrome. * **Option C (Hypertension with oral lesions):** This is incomplete. While hypertension and oral lichen planus are components, the syndrome specifically requires the presence of the metabolic component (Diabetes) to complete the triad. * **Option D (Pemphigus, CHF, diabetes):** There is no recognized clinical syndrome linking these three specific conditions. Pemphigus is an autoimmune blistering disorder unrelated to the Grinspan triad. #### High-Yield Clinical Pearls for NEET-PG: * **Oral Lichen Planus (OLP):** Most commonly presents as the **reticular type** with Wickham’s striae. In Grinspan syndrome, the erosive type is frequently seen. * **Mnemonic:** Remember the **"3 H's"** (though one is D): **H**ypertension, **H**yperglycemia (Diabetes), and **H**yperkeratotic oral lesions (Lichen Planus). * **Differential Diagnosis:** Always rule out a **Lichenoid Drug Eruption** when a patient presents with this triad, as the lesions may resolve upon changing antihypertensive medications.

Q: Heliotrope sign is typically seen in which of the following conditions?

Dermatomyositis. **Explanation:** **Dermatomyositis** is an idiopathic inflammatory myopathy characterized by proximal muscle weakness and pathognomonic cutaneous findings. The **Heliotrope sign** is a hallmark feature consisting of a symmetric, violaceous (purplish) to erythematous rash on the upper eyelids, often accompanied by periorbital edema. It is named after the heliotrope flower (*Heliotropium*) due to its similar color. The underlying pathology involves a microangiopathy affecting the skin and muscles. **Analysis of Incorrect Options:** * **Scleroderma:** Characterized by skin thickening (sclerosis), Raynaud’s phenomenon, and "beaked nose" or "microstomia" (small mouth). It does not present with a violaceous eyelid rash. * **Photodermatitis:** While this involves sun-exposed areas, it typically presents as eczematous or polymorphic eruptions. It lacks the specific violaceous hue and periorbital distribution characteristic of the Heliotrope sign. * **Vitiligo:** An autoimmune destruction of melanocytes resulting in depigmented (chalky white) macules and patches, not inflammatory rashes. **High-Yield Clinical Pearls for NEET-PG:** * **Gottron’s Papules:** Violaceous, lichenoid papules over the dorsal aspect of interphalangeal and metacarpophalangeal joints (Pathognomonic). * **Shawl Sign:** Erythema over the upper back and shoulders. * **V-Sign:** Erythema over the anterior neck and upper chest. * **Mechanic’s Hands:** Hyperkeratosis and fissuring of the lateral and palmar aspects of the fingers (associated with Anti-Jo-1 antibodies). * **Malignancy:** Dermatomyositis in adults is significantly associated with internal malignancies (e.g., ovarian, lung, gastric).

Q: In pemphigus foliaceous, acantholysis is seen in which layer of the epidermis?

Stratum basale. **Explanation:** In **Pemphigus Foliaceus (PF)**, the pathology is characterized by **subcorneal acantholysis**. The autoantibodies (IgG) are directed against **Desmoglein 1 (Dsg1)**. Since Dsg1 is primarily expressed in the upper layers of the epidermis, the loss of cell-to-cell adhesion occurs superficially, specifically in the **stratum granulosum**. *Note: There appears to be a discrepancy in the provided key. In standard dermatopathology, PF occurs in the granular layer, while Pemphigus Vulgaris occurs just above the basal layer.* **Analysis of Options:** * **Stratum Granulosum (Correct Pathological Site):** This is the classic site for PF. Because the split is so superficial, the blisters are fragile and often present clinically as erosions or "corn-flake" scales rather than intact bullae. * **Stratum Basale (Incorrect):** This layer remains attached to the basement membrane in Pemphigus Vulgaris, creating the "tombstone appearance." Acantholysis *at* the basal layer is not characteristic of PF. * **Stratum Corneum (Incorrect):** While the split is "subcorneal," the actual cellular breakdown (acantholysis) occurs in the living cells of the granulosum immediately beneath it. * **Spinous Layer (Incorrect):** This is the site of acantholysis in **Pemphigus Vulgaris**, where antibodies target **Desmoglein 3** (and Dsg1), leading to deeper, suprabasal clefting. **NEET-PG High-Yield Pearls:** 1. **Target Antigen:** Dsg1 only (PF); Dsg3 +/- Dsg1 (PV). 2. **Clinical Sign:** Nikolsky sign is positive in both, but PF lacks mucosal involvement (Dsg3 compensates in mucosa). 3. **Immunofluorescence:** "Fish-net" or "Lace-like" IgG deposition in the intercellular spaces. 4. **Fogo Selvagem:** An endemic form of Pemphigus Foliaceus linked to black fly bites (Simulium species).

Q: The Pathergy test is positive in which of the following conditions?

Behcet's disease. **Explanation:** **Behcet’s Disease (Correct Answer):** The Pathergy test is a hallmark diagnostic tool for Behcet’s disease. It represents a state of **cutaneous vascular hyper-reactivity** to minor trauma. The test is performed by pricking the skin (usually the forearm) with a sterile 20-gauge needle. A positive result is defined by the formation of a sterile erythematous papule or pustule (>2 mm) at the site within 24–48 hours. While highly specific for Behcet’s, its sensitivity varies geographically (highest in Silk Road populations). **Incorrect Options:** * **Richter’s Disease (Option A):** This refers to Richter’s Transformation, where a low-grade B-cell lymphoma (like CLL) transforms into an aggressive high-grade diffuse large B-cell lymphoma. It has no association with skin hyper-reactivity. * **Ritter’s Disease (Option C):** Also known as **Staphylococcal Scalded Skin Syndrome (SSSS)**, this is caused by exfoliative toxins from *Staphylococcus aureus*. It presents with widespread bullae and a positive Nikolsky sign, not pathergy. * **Erythema Multiforme (Option D):** A hypersensitivity reaction (often triggered by HSV or Mycoplasma) characterized by "target" or "iris" lesions. It does not involve pathergy. **Clinical Pearls for NEET-PG:** 1. **Other Pathergy-positive conditions:** Pyoderma Gangrenosum, Sweet Syndrome, and occasionally Crohn’s disease. 2. **Behcet’s Triad:** Recurrent oral ulcers (most common), genital ulcers (most specific), and uveitis. 3. **HLA Association:** Strongly associated with **HLA-B51**. 4. **Histopathology:** A positive pathergy test histologically shows a heavy neutrophilic infiltrate (leukocytoclastic vasculitis).

Question 1

A 28-year-old female presents with a 3-month history of violaceous, flat-topped papules on her wrists and lower back associated with intense pruritus. Examination reveals white lacy streaks on the buccal mucosa bilaterally. She was recently started on antihypertensive medication 4 months ago. Histopathology shows hyperkeratosis, irregular acanthosis, and band-like lymphocytic infiltrate at the dermoepidermal junction. What is the most appropriate next step in management?

Accepted Answer

Discontinue current antihypertensive and start topical corticosteroids

Answer

Start oral prednisolone 1 mg/kg and continue current antihypertensive

Answer

Start oral methotrexate and continue current antihypertensive

Answer

Perform direct immunofluorescence and continue current medication

Question 2

A study of persons developing skin lesions following sun exposure is conducted. The lesions are not found on skin protected from ultraviolet light. Biopsies of involved skin show immunoglobulin G deposition along the dermal-epidermal junction, along with vacuolization of the basal layer and a perivascular lymphocytic infiltrate. No other organ involvement is present. Which of the following diseases do these patients most likely have?

Accepted Answer

Discoid lupus erythematosus

Answer

Bullous pemphigoid

Answer

Celiac disease

Answer

Dysplastic nevus syndrome

Question 3

Gottron's papules are a characteristic clinical finding in which of the following conditions?

Accepted Answer

Dermatomyositis

Answer

Sarcoidosis

Answer

Scleroderma

Answer

Fungal infection

Question 4

Salt and pepper dyschromatosis is seen in which of the following conditions?

Accepted Answer

Scleroderma

Answer

Dermatofibrositis

Answer

Systemic Lupus Erythematosus (SLE)

Answer

Psoriasis

Question 5

Which of the following drugs is not associated with drug-induced pemphigus?

Accepted Answer

Furosemide

Answer

Rifampicin

Answer

Penicillin

Answer

Captopril

Question 6

A 25-year-old man complains of eruptions of blisters on his scalp, inner surface of the groin, and in his mouth. The blisters rupture easily and leave large crusted areas. Histologically, the lesions show separation of the stratum spinosum from the basal layer. The results of direct immunofluorescence microscopy for IgG are shown. Which of the following proteins is targeted by IgG autoantibody in the skin of this patient?

Accepted Answer

Desmoglein-3

Answer

Collagen type IV

Answer

E-cadherin

Answer

Fibronectin

Question 7

Grinspan syndrome is associated with which of the following conditions?

Accepted Answer

Hypertension, diabetes, lichen planus

Answer

Oral, ocular, genital lesions

Answer

Hypertension with oral lesions

Answer

Pemphigus, congestive heart failure, diabetes

Question 8

Heliotrope sign is typically seen in which of the following conditions?

Accepted Answer

Dermatomyositis

Answer

Scleroderma

Answer

Photodermatitis

Answer

Vitiligo

Question 9

In pemphigus foliaceous, acantholysis is seen in which layer of the epidermis?

Accepted Answer

Stratum basale

Answer

Stratum corneum

Answer

Stratum granulosum

Answer

Spinous layer

Question 10

The Pathergy test is positive in which of the following conditions?

Accepted Answer

Behcet's disease

Answer

Richter's disease

Answer

Ritter's disease

Answer

Erythema multiforme

Autoimmune Skin Diseases — MCQs

Autoimmune Skin Diseases — MCQs

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