Autoimmune Skin Diseases Practice Questions

Q: A patient develops progressive skin thickening after a failed kidney transplant. What is the most likely diagnosis?

Nephrogenic fibrosing dermopathy. **Explanation:** The correct diagnosis is **Nephrogenic Fibrosing Dermopathy (NFD)**, now more commonly referred to as **Nephrogenic Systemic Fibrosis (NSF)**. **Why it is correct:** NFD is a rare, systemic fibrosing disorder seen exclusively in patients with renal impairment (acute or chronic). It is strongly associated with exposure to **Gadolinium-based contrast agents** used during MRI. In this clinical scenario, a failed kidney transplant implies chronic kidney disease (CKD), which is the primary risk factor. The condition presents as progressive skin thickening, woody induration, and "cobblestone" plaques, typically affecting the extremities while sparing the face. **Why other options are incorrect:** * **Eosinophilic fasciitis (Shulman syndrome):** Presents with "orange peel" (peau d'orange) skin and the "groove sign" over veins. It is usually triggered by strenuous exercise and is characterized by peripheral eosinophilia, not renal failure. * **Myxedema:** Associated with thyroid dysfunction. Pretibial myxedema (Graves' disease) presents with waxy, translucent papules/plaques, while generalized myxedema (hypothyroidism) causes non-pitting edema. * **Scleroderma (Systemic Sclerosis):** While it causes skin thickening, it is characterized by Raynaud’s phenomenon, facial involvement (microstomia), and specific autoantibodies (anti-Scl70, anti-centromere), which are absent in NFD. **High-Yield Clinical Pearls for NEET-PG:** * **Trigger:** Gadolinium exposure in patients with GFR < 30 mL/min. * **Clinical Feature:** Symmetrical skin involvement; unlike scleroderma, it **spares the face**. * **Histology:** Proliferation of spindle-shaped fibroblasts (CD34+), increased collagen, and elastic fibers. * **Prognosis:** Can lead to joint contractures and internal organ fibrosis (lungs, heart).

Q: In Pemphigus Vulgaris, autoantibodies are formed against which of the following cell adhesion molecules?

Cadherin. **Explanation:** **Pemphigus Vulgaris (PV)** is an autoimmune blistering disease characterized by the loss of cell-to-cell adhesion between keratinocytes, a process known as **acantholysis**. 1. **Why Cadherin is correct:** The primary pathology in PV involves IgG autoantibodies directed against **Desmogleins (Dsg1 and Dsg3)**. Desmogleins are transmembrane glycoproteins that belong to the **Cadherin** superfamily of calcium-dependent cell adhesion molecules. They are the core components of **desmosomes**, which provide structural integrity to the epidermis. In PV, Dsg3 (with or without Dsg1) is targeted, leading to intraepidermal cleavage just above the basal layer (suprabasal split). 2. **Why other options are incorrect:** * **Selectins:** These are involved in the "rolling" phase of leukocyte extravasation during inflammation, not in stable cell-to-cell adhesion in the epidermis. * **Integrins:** These primarily mediate cell-to-matrix adhesion (binding cells to the basement membrane). They are involved in diseases like Cicatricial Pemphigoid, not Pemphigus. * **IGSF CAM (Immunoglobulin Superfamily):** These molecules (like ICAM-1 and VCAM-1) are involved in immune cell interactions and firm adhesion during leukocyte migration. **High-Yield Clinical Pearls for NEET-PG:** * **Target Antigens:** PV = Dsg3 (Mucosal) and Dsg1 (Cutaneous); Pemphigus Foliaceus = Dsg1 only. * **Histopathology:** "Row of tombstones" appearance (basal cells remain attached to the basement membrane via integrins/hemidesmosomes). * **Immunofluorescence:** "Fish-net" or "Lace-like" pattern of IgG/C3 deposits. * **Clinical Signs:** Positive Nikolsky sign and Bulla spread sign (Asboe-Hansen sign). * **Oral Involvement:** PV almost always presents with painful oral erosions before skin blisters appear.

Q: In Pemphigus vulgaris, autoantibodies are formed against which cell adhesion molecule?

Cadherin. **Pemphigus vulgaris (PV)** is an autoimmune blistering disease characterized by the loss of intercellular adhesion between keratinocytes, a process known as **acantholysis** [1]. 1. **Why Cadherin is correct:** The primary pathology in PV involves IgG autoantibodies directed against **Desmogleins (Dsg1 and Dsg3)**. Desmogleins are calcium-dependent adhesion molecules belonging to the **Cadherin family**. They are integral components of **desmosomes**, which provide structural integrity by linking the intermediate filaments of adjacent cells. The destruction of these cadherins leads to the characteristic "row of tombstone" appearance on histology and suprabasal blistering [1][2]. 2. **Why other options are incorrect:** * **Selectins (A):** These are involved in the initial "rolling" phase of leukocyte extravasation during inflammation, not cell-to-cell structural adhesion. * **Integrins (C):** These primarily mediate cell-to-matrix adhesion (linking cells to the basement membrane). Antibodies against integrins or hemidesmosomal proteins (like BP180) are seen in **Bullous Pemphigoid**, not PV [1]. * **IgSF CAMs (D):** The Immunoglobulin Superfamily CAMs (e.g., ICAM-1, VCAM-1) are involved in immune cell recognition and firm adhesion during inflammation. **High-Yield Clinical Pearls for NEET-PG:** * **Target Antigens:** Dsg3 (mucosal-dominant) and Dsg1 (mucocutaneous). * **Immunofluorescence:** Shows a characteristic **"fishnet" or "lace-like"** pattern of IgG and C3 deposits in the epidermis [1]. * **Nikolsky Sign:** Positive (bulla spreads with lateral pressure). * **Tzanck Smear:** Shows **Acantholytic cells** (Tzanck cells)—large, round keratinocytes with hyperchromatic nuclei. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Skin, p. 1172. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Skin, pp. 1170-1172.

Q: Suprabasal acantholytic blisters are seen in which condition?

Pemphigus vulgaris. **Explanation:** The hallmark of **Pemphigus vulgaris (PV)** is the presence of **suprabasal acantholytic blisters**. This occurs due to IgG antibodies directed against **Desmoglein 3** (and sometimes Desmoglein 1), which are components of desmosomes. The loss of intercellular adhesion (acantholysis) just above the basal layer results in a "row of tombstones" appearance, where the basal cells remain attached to the basement membrane while the upper layers detach. **Analysis of Options:** * **Pemphigus foliaceus:** Characterized by **subcorneal** (superficial) blisters. The antibodies target Desmoglein 1, which is primarily expressed in the upper layers of the epidermis. * **Bullous pemphigoid:** A **subepidermal** blistering disease. It involves antibodies against BP180 and BP230 in the hemidesmosomes, leading to a split between the epidermis and dermis. * **Dermatitis herpetiformis:** Also a **subepidermal** disease associated with Celiac disease. It is characterized by IgA deposits at the tips of dermal papillae (microabscesses). **High-Yield Clinical Pearls for NEET-PG:** * **Nikolsky Sign:** Positive in PV (due to intraepidermal split) but negative in Bullous pemphigoid. * **Tzanck Smear:** Shows **Acantholytic cells** (Tzanck cells/Tzank cells) which are rounded keratinocytes with hyperchromatic nuclei. * **Immunofluorescence:** PV shows a characteristic **"fish-net" or "lace-like"** pattern of IgG/C3 deposition. * **Clinical Presentation:** PV typically starts with painful **oral ulcers** before progressing to flaccid skin bullae.

Q: A 70-year-old man develops multiple pruritic skin lesions and bullae mostly in the axillae and around the medial aspects of his groin and thighs. Some lesions are present on his forearms and lower legs, with moderately painful oral lesions. Nikolsky sign is negative, and there is no eye involvement. Which of the following is the most likely diagnosis?

Bullous pemphigoid. ### Explanation **Bullous Pemphigoid (BP)** is the most likely diagnosis based on the clinical presentation. It is an autoimmune subepidermal blistering disease typically affecting the elderly (60–80 years). **Why Option C is Correct:** * **Clinical Presentation:** BP characteristically presents with large, **tense bullae** on an erythematous or eczematous base. The lesions are intensely **pruritic** and favor flexural areas like the axillae, groin, and inner thighs. * **Nikolsky Sign:** Since the split occurs at the dermo-epidermal junction (subepidermal), the epidermis is intact and firm; thus, the Nikolsky sign is **negative**. * **Mucosal Involvement:** Unlike Pemphigus, oral involvement is less common (seen in ~10–20% of cases) and usually less severe. **Why Other Options are Incorrect:** * **A. Dermatitis Herpetiformis:** Associated with Celiac disease; presents as extremely itchy, grouped (herpetiform) vesicles on extensor surfaces (elbows, knees). * **B. Pemphigus Vulgaris:** Characterized by **flaccid bullae** that rupture easily, a **positive Nikolsky sign**, and near-universal, severe oral involvement. It is an intraepidermal disorder. * **D. Cicatricial Pemphigoid (Mucous Membrane Pemphigoid):** Primarily affects mucous membranes (especially the eyes/conjunctiva, leading to scarring/symblepharon). The question explicitly states there is no eye involvement. **High-Yield Pearls for NEET-PG:** * **Target Antigens:** BP180 (Type XVII Collagen) and BP230. * **Histopathology:** Subepidermal blister with an inflammatory infiltrate rich in **eosinophils**. * **Direct Immunofluorescence (DIF):** Shows **linear** IgG and C3 deposits along the basement membrane zone ("Linear n-serrated pattern"). * **Treatment:** Potent topical corticosteroids (e.g., Clobetasol) are first-line for localized/moderate disease; systemic steroids for generalized cases.

Q: Intercellular IgG deposition in the epidermis is seen in which of the following conditions?

Pemphigus. **Explanation:** The correct answer is **Pemphigus**. This group of autoimmune blistering diseases is characterized by the presence of IgG autoantibodies directed against **desmogleins** (transmembrane glycoproteins of desmosomes). On Direct Immunofluorescence (DIF), these antibodies appear as **intercellular IgG and C3 deposition** throughout the epidermis, creating a characteristic **"fishnet" or "chicken-wire" pattern**. This leads to loss of cell-to-cell adhesion, a process known as **acantholysis**. **Analysis of Incorrect Options:** * **Subcorneal Pustular Dermatosis (Sneddon-Wilkinson disease):** This is a sterile neutrophilic dermatosis. DIF is typically **negative** for immunoglobulin deposition. * **Bullous Pemphigoid:** This is a subepidermal blistering disease where IgG and C3 are deposited in a **linear pattern along the dermo-epidermal junction (basement membrane zone)**, targeting Hemidesmosomes (BP180/BP230). * **Dermatitis Herpetiformis:** Associated with celiac disease, this condition shows **granular IgA deposition** at the **tips of dermal papillae**. **High-Yield Clinical Pearls for NEET-PG:** * **Pemphigus Vulgaris:** Most common type; involves Desmoglein 3 (±1); presents with oral ulcers and a **positive Nikolsky sign**. * **Tzanck Smear:** Look for **Acantholytic cells** (Tzanck cells)—large, round keratinocytes with hyperchromatic nuclei. * **Histopathology:** Pemphigus vulgaris shows "row of tombstones" appearance at the basal layer. * **Treatment:** Systemic corticosteroids are the mainstay; Rituximab is now a first-line biological option.

Q: Tense itching bulla is seen in?

Bullous pemphigoid. **Explanation:** The hallmark of **Bullous Pemphigoid (BP)** is the presence of **tense, large bullae** occurring on an erythematous or normal skin base, typically accompanied by **intense pruritus (itching)**. 1. **Why Bullous Pemphigoid is correct:** BP is an autoimmune subepidermal blistering disease caused by IgG antibodies against hemidesmosomal proteins (**BP180 and BP230**). Because the split occurs deep at the dermo-epidermal junction, the "roof" of the blister consists of the entire epidermis. This makes the blister structurally strong and **tense**, meaning it does not rupture easily (Negative Nikolsky sign). 2. **Why other options are incorrect:** * **Dermatitis Herpetiformis:** Characterized by extremely itchy, small, grouped vesicles (herpetiform) on extensor surfaces. While it is itchy, it presents as **vesicles**, not large tense bullae. * **Pemphigus Vulgaris:** An intraepidermal disease (targeting Desmoglein 3). Because the split is superficial, the blisters are **flaccid** and rupture easily, leaving painful erosions. It is typically painful, not itchy. * **Erythema Multiforme:** Characterized by classic **"target" or "iris" lesions**. While bullae can occur in severe cases, they are not the primary diagnostic feature, and the clinical context (post-infections like HSV) differs. **High-Yield Clinical Pearls for NEET-PG:** * **Nikolsky Sign:** Negative in BP; Positive in Pemphigus Vulgaris. * **Direct Immunofluorescence (DIF):** Shows **linear** IgG and C3 deposits along the basement membrane zone. * **Histopathology:** Subepidermal blister with an inflammatory infiltrate rich in **eosinophils**. * **Demographics:** Typically affects the elderly (>60 years).

Question 1

A 50-year-old man has a 2-year history of facial bullae and oral ulcers. A microscopic smear from skin lesions is most likely to disclose what?

Accepted Answer

Acantholytic cells

Answer

Tzanck cells

Answer

Necrosis

Answer

Koilocytosis

Question 2

A patient develops progressive skin thickening after a failed kidney transplant. What is the most likely diagnosis?

Accepted Answer

Nephrogenic fibrosing dermopathy

Answer

Eosinophilic fasciitis

Answer

Myxedema

Answer

Scleroderma

Question 3

In Pemphigus Vulgaris, autoantibodies are formed against which of the following cell adhesion molecules?

Accepted Answer

Cadherin

Answer

Selectin

Answer

Integrin

Answer

IGSF CAM

Question 4

In Pemphigus vulgaris, autoantibodies are formed against which cell adhesion molecule?

Accepted Answer

Cadherin

Answer

Selectin

Answer

Integrin

Answer

IgSF CAM

Question 5

A patient presents with recurrent oral ulcers. The ulcers are small with a yellow floor surrounded by an erythematous halo on the lips. The patient also has multiple, tender nodules on the shins. What is the probable diagnosis?

Accepted Answer

Behcet's syndrome

Answer

Pemphigus vulgaris

Answer

Herpes Labialis

Answer

Fixed drug eruption

Question 6

Suprabasal acantholytic blisters are seen in which condition?

Accepted Answer

Pemphigus vulgaris

Answer

Dermatitis herpetiformis

Answer

Bullous pemphigoid

Answer

Pemphigus foliaceus

Question 7

A 70-year-old man develops multiple pruritic skin lesions and bullae mostly in the axillae and around the medial aspects of his groin and thighs. Some lesions are present on his forearms and lower legs, with moderately painful oral lesions. Nikolsky sign is negative, and there is no eye involvement. Which of the following is the most likely diagnosis?

Accepted Answer

Bullous pemphigoid

Answer

Dermatitis herpetiformis

Answer

Pemphigus vulgaris

Answer

Cicatricial pemphigoid

Question 8

Intercellular IgG deposition in the epidermis is seen in which of the following conditions?

Accepted Answer

Pemphigus

Answer

Subcorneal pustular dermatosis

Answer

Bullous pemphigoid

Answer

Dermatitis herpetiformis

Question 9

A 30-year-old woman presents with scattered scalp lesions that she has had for the past several months and that are causing hair loss. The lesions have hyperpigmented and depigmented areas with follicular plugging and atrophy. Which of the following is the best treatment for this patient?

Accepted Answer

Topical steroids

Answer

Griseofulvin

Answer

Ketoconazole cream

Answer

Ketoconazole shampoo

Question 10

Tense itching bulla is seen in?

Accepted Answer

Bullous pemphigoid

Answer

Dermatitis herpetiformis

Answer

Pemphigus vulgaris

Answer

Erythema multiforme

Autoimmune Skin Diseases — MCQs

Autoimmune Skin Diseases — MCQs

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