Blistering Diseases — MCQs

A 15-year-old girl complains of itchy skin lesions of 6 months in duration. Physical examination reveals numerous wheal-like lesions with small vesicles over her elbows and knees. A skin biopsy demonstrates inflammation in the tips of the dermal papillae and subepidermal vesicles. Which of the following histopathologic findings would provide the best evidence to support a diagnosis of dermatitis herpetiformis in this patient?

Blistering Diseases Indian Medical PG Practice Questions and MCQs

Question 71: Acantholysis, resulting from desmosome weakening by autoantibodies directed against the protein desmoglein, is the disease mechanism attributed to which of the following?

A. Epidermolysis bullosa
B. Mucous membrane pemphigoid
C. Pemphigus vulgaris (Correct Answer)
D. Herpes simplex infections

Explanation: ### Explanation **Correct Answer: C. Pemphigus vulgaris** **Mechanism:** Pemphigus vulgaris (PV) is an autoimmune blistering disease characterized by **acantholysis**—the loss of cell-to-cell adhesion between keratinocytes. This occurs because IgG autoantibodies target **Desmoglein 3** (and sometimes Desmoglein 1), which are critical transmembrane glycoproteins of the **desmosomes**. When these desmosomes are disrupted, keratinocytes detach from one another, leading to the formation of intraepidermal blisters. Because the basal layer remains attached to the basement membrane via hemidesmosomes, it creates the classic "tombstone appearance" on histology. **Why other options are incorrect:** * **A. Epidermolysis bullosa:** This is a group of *genetic* (not autoimmune) mechanobullous disorders caused by mutations in structural proteins like keratins (EB Simplex) or laminin/collagen (Junctional/Dystrophic EB). * **B. Mucous membrane pemphigoid:** This is an autoimmune disease, but the antibodies target the **basement membrane zone** (specifically BP180 or laminin 332) in hemidesmosomes, leading to *subepidermal* blisters, not acantholysis. * **D. Herpes simplex infections:** While HSV causes intraepidermal vesicles, the mechanism is viral-induced **ballooning degeneration** and cytolysis, not an autoimmune attack on desmogleins. **High-Yield NEET-PG Pearls:** * **Nikolsky Sign:** Positive in Pemphigus vulgaris (due to acantholysis); negative in Bullous Pemphigoid. * **Tzanck Smear:** Shows rounded, detached keratinocytes with hyperchromatic nuclei called **Acantholytic or Tzanck cells**. * **Direct Immunofluorescence (DIF):** Shows a characteristic **"fishnet" or "lace-like"** pattern of IgG/C3 deposits. * **Clinical Presentation:** Often starts with painful oral ulcers before progressing to flaccid skin bullae.

Question 72: All of the following are true about linear IgA disease except:

A. Subepidermal involvement
B. Severe itching
C. Granular deposition of IgA (Correct Answer)
D. All of the above

Explanation: **Explanation:** Linear IgA Bullous Dermatosis (LABD) is an autoimmune subepidermal blistering disease characterized by the presence of IgA antibodies directed against the basement membrane zone (BMZ). **Why Option C is correct:** The hallmark of this disease, as the name suggests, is the **linear deposition of IgA** along the dermo-epidermal junction (DEJ) on direct immunofluorescence (DIF). **Granular deposition** of IgA is characteristic of **Dermatitis Herpetiformis**, not Linear IgA disease. This distinction is a high-yield point for NEET-PG. **Analysis of other options:** * **Option A (Subepidermal involvement):** This is a true statement. The autoantibodies target the 120 kDa or 97 kDa fragments of BP180 (Type XVII collagen) in the lamina lucida, leading to a split below the epidermis. * **Option B (Severe itching):** This is true. Patients often present with intense pruritus and burning sensations, similar to Dermatitis Herpetiformis. **Clinical Pearls for NEET-PG:** 1. **Morphology:** Classically presents as vesicles or bullae in a **"string of beads"** or **"rosette-like"** configuration. 2. **Drug-Induced:** The most common drug trigger is **Vancomycin**. 3. **Treatment:** The drug of choice is **Dapsone**. 4. **Histopathology:** Shows subepidermal blisters with a predominantly neutrophilic infiltrate (microabscesses at the papillary tips). 5. **Childhood variant:** Also known as Chronic Bullous Disease of Childhood (CBDC).

Question 73: A 60-year-old male patient presented with tense blisters over the trunk and thighs for 2 weeks. The lesions are mildly itchy and have an erythematous base. Nikolsky's sign is negative, and there is no mucosal involvement. What is the most likely diagnosis?

A. Pemphigus vulgaris
B. Pemphigus vegetans
C. Bullous pemphigoid (Correct Answer)
D. Dermatitis herpetiformis

Explanation: **Explanation:** The clinical presentation is classic for **Bullous Pemphigoid (BP)**. The key diagnostic features in this case are the **tense blisters** and the **negative Nikolsky’s sign**. In BP, autoantibodies (anti-BP180 and anti-BP230) target the hemidesmosomes at the dermo-epidermal junction. This results in **subepidermal** splitting. Because the entire epidermis forms the roof of the blister, it is structurally strong and "tense," making Nikolsky’s sign negative. BP typically affects the elderly (60+ years) and often spares the mucosa. **Why other options are incorrect:** * **Pemphigus vulgaris:** Characterized by **flaccid** bullae due to intraepidermal splitting (acantholysis). Nikolsky’s sign is positive, and mucosal involvement is almost always present. * **Pemphigus vegetans:** A variant of pemphigus vulgaris that presents with hypertrophic, verrucous (wart-like) lesions in intertriginous areas, not generalized tense blisters. * **Dermatitis herpetiformis:** Presents with intensely pruritic, grouped (herpetiform) vesicles, typically on extensor surfaces (elbows, knees). It is strongly associated with Celiac disease and shows IgA deposits on immunofluorescence. **High-Yield Clinical Pearls for NEET-PG:** * **Target Antigens:** BP180 (Type XVII Collagen) is the most common target in BP. * **Direct Immunofluorescence (DIF):** Shows **linear** IgG and C3 deposits along the basement membrane zone. * **Histopathology:** Subepidermal blister with an inflammatory infiltrate rich in **eosinophils**. * **Treatment:** Potent topical corticosteroids (e.g., Clobetasol) or systemic steroids are the first-line management.

Question 74: A 30-year-old male presents with itchy papulo-vesicular lesions on the extremities, knees, elbows, and buttocks for one year. Direct immunofluorescence staining of the lesions showed IgA deposition at the dermoepidermal junction. Which of the following represents the most probable diagnosis?

A. Pemphigus vulgaris
B. Bullous pemphigoid
C. Dermatitis herpetiformis (Correct Answer)
D. Nummular eczema

Explanation: **Explanation:** The clinical presentation and immunofluorescence findings are classic for **Dermatitis Herpetiformis (DH)**. **1. Why the correct answer is right:** Dermatitis herpetiformis is a chronic, intensely pruritic autoimmune blistering disease. The key diagnostic features present in this case are: * **Clinical Presentation:** Symmetrical, grouped (herpetiform) papulo-vesicles typically involving the **extensor surfaces** (elbows, knees), buttocks, and back. * **Direct Immunofluorescence (DIF):** The hallmark is **granular IgA deposits** at the tips of the dermal papillae (dermoepidermal junction). * **Pathophysiology:** It is strongly associated with **Gluten-sensitive enteropathy (Celiac disease)**, mediated by IgA antibodies against tissue transglutaminase (tTG) and epidermal transglutaminase (eTG). **2. Why the incorrect options are wrong:** * **Pemphigus vulgaris:** Characterized by flaccid bullae and oral mucosal involvement. DIF shows **IgG and C3** in a "fishnet" or "lace-like" pattern (intercellular) within the epidermis. * **Bullous pemphigoid:** Typically affects the elderly with large, tense bullae. DIF shows **linear IgG and C3** along the basement membrane zone. * **Nummular eczema:** Presents as coin-shaped, itchy, eczematous plaques. It is not an autoimmune blistering disease and would show negative DIF for IgA. **High-Yield Clinical Pearls for NEET-PG:** * **Gold Standard Diagnosis:** DIF of **perilesional skin** (not the blister itself). * **Histopathology:** Shows **subepidermal blisters** with **neutrophilic microabscesses** at the dermal papillary tips. * **Treatment of Choice:** **Dapsone** (provides rapid relief of itch) along with a **Gluten-free diet**. * **HLA Association:** Strongly associated with **HLA-DQ2** and **HLA-DQ8**.

Question 75: Which of the following tests would be MOST useful for confirmation of Pemphigus vulgaris?

A. Bacterial culture
B. Complete blood count
C. Fungal culture
D. Tissue biopsy with direct immunofluorescence (Correct Answer)

Explanation: **Explanation:** **Pemphigus vulgaris (PV)** is an autoimmune bullous disorder characterized by the formation of intraepidermal blisters. The pathogenesis involves IgG autoantibodies directed against **Desmoglein 3** (and sometimes Desmoglein 1), which are components of desmosomes. This leads to **acantholysis** (loss of keratinocyte adhesion). **Why Option D is Correct:** The gold standard for confirming a diagnosis of Pemphigus vulgaris is a **tissue biopsy** combined with **Direct Immunofluorescence (DIF)**. * **Histopathology:** Shows suprabasal splitting and "tombstoning" of the basal layer. * **DIF:** Performed on perilesional skin, it reveals a characteristic **"fish-net" or "chicken-wire" pattern** of IgG and C3 deposits along the intercellular substance of the epidermis. This confirms the presence and location of the autoantibodies. **Why Other Options are Incorrect:** * **A & C (Bacterial/Fungal Culture):** PV is an autoimmune disease, not an infectious one. While secondary infections can occur in denuded skin, cultures do not diagnose the primary pathology. * **B (Complete Blood Count):** CBC is non-specific. While it might show leukocytosis in cases of secondary infection, it cannot confirm an autoimmune blistering disorder. **High-Yield Clinical Pearls for NEET-PG:** * **Nikolsky Sign:** Positive (extension of a blister or denudation of skin upon lateral pressure). * **Tzanck Smear:** Shows **Acantholytic cells (Tzanck cells)**—large, round keratinocytes with hyperchromatic nuclei. * **Indirect Immunofluorescence (IIF):** Used to detect circulating antibodies; titers often correlate with disease activity. * **First-line Treatment:** Systemic corticosteroids (e.g., Prednisolone).

Question 76: Selective granular IgA deposit at dermal papillae tips is seen in which condition?

A. Bullous pemphigoid
B. Dermatitis herpetiformis (Correct Answer)
C. Lichen planus
D. Pemphigus vulgaris

Explanation: ### Explanation **Correct Answer: B. Dermatitis herpetiformis** **Mechanism and Immunopathology:** Dermatitis herpetiformis (DH) is a cutaneous manifestation of gluten-sensitive enteropathy (Celiac disease). The hallmark of this condition is the presence of **granular IgA deposits** localized specifically at the **tips of the dermal papillae**. These deposits are formed by IgA antibodies directed against **epidermal transglutaminase (eTG)**, which cross-react with tissue transglutaminase (tTG) in the gut. This deposition triggers the recruitment of neutrophils, leading to the formation of microabscesses (Knot’s microabscesses) and subsequent subepidermal blistering. **Why other options are incorrect:** * **Bullous pemphigoid:** Characterized by **linear IgG and C3** deposits along the basement membrane zone (BMZ). It targets BP180 and BP230. * **Lichen planus:** Does not typically show specific diagnostic IgA/IgG patterns on Direct Immunofluorescence (DIF), though globular IgM deposits (Cytoid bodies) may be seen at the dermo-epidermal junction. * **Pemphigus vulgaris:** Characterized by **IgG and C3** deposits in a **"fish-net" or "lace-like"** pattern within the intercellular spaces of the epidermis (targeting Desmoglein 3 and 1). **High-Yield Clinical Pearls for NEET-PG:** * **Clinical Presentation:** Intensely pruritic, symmetrical vesicles on extensor surfaces (elbows, knees, buttocks). * **Histopathology:** Subepidermal blister with **neutrophilic microabscesses** at dermal papillary tips. * **Association:** Strongly associated with **HLA-DQ2 and HLA-DQ8**. * **Treatment of Choice:** **Dapsone** (provides rapid symptomatic relief) and a strict **Gluten-free diet** (long-term management). * **Gold Standard Diagnosis:** Direct Immunofluorescence (DIF) of perilesional (uninvolved) skin showing granular IgA.

Question 77: Subepidermal bulla are seen in which of the following conditions?

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

Explanation: ### Explanation **1. Why Pemphigoid is Correct:** Bullous Pemphigoid (BP) is the classic example of a **subepidermal** blistering disease. The underlying pathophysiology involves autoantibodies (IgG) directed against **BP180 and BP230** proteins within the hemidesmosomes. These proteins anchor the basal layer of the epidermis to the dermis. When these are targeted, the entire epidermis detaches from the dermis, creating a "subepidermal" cleft. Because the roof of the blister consists of the full thickness of the epidermis, the bullae are characteristically **tense** and less likely to rupture easily. **2. Why the Other Options are Incorrect:** * **Pemphigus (B):** This group of diseases (e.g., Pemphigus Vulgaris) is characterized by **intraepidermal** blisters. Autoantibodies target desmogleins (cell-to-cell adhesion), leading to acantholysis (loss of keratinocyte cohesion). Blisters are **flaccid** and rupture easily (Positive Nikolsky sign). * **Pityriasis Rosea (C):** This is a papulosquamous disorder, not a primary blistering disease. It is characterized by a "Herald patch" followed by a "Christmas tree" distribution of scaly plaques. * **Psoriasis (D):** This is a chronic inflammatory condition characterized by epidermal hyperplasia (acanthosis) and parakeratosis. While "Munro’s microabscesses" (neutrophils in the stratum corneum) are seen, it does not typically present with bullae. **3. NEET-PG High-Yield Pearls:** * **Subepidermal Blisters (Mnemonic: "D-E-B-C-H"):** **D**ermatitis herpetiformis, **E**pidermolysis bullosa acquisita, **B**ullous pemphigoid, **C**icatricial pemphigoid, **H**erpes gestationis. * **Immunofluorescence (BP):** Direct Immunofluorescence (DIF) shows **linear IgG and C3** deposits along the basement membrane zone. * **Histology:** Look for a subepidermal split with an infiltrate often rich in **eosinophils**.

Question 78: What is the commonest variety of pemphigus?

A. Pemphigus vulgaris (Correct Answer)
B. Pemphigus vegetans
C. Pemphigus foliaceus
D. Pemphigus erythematosus

Explanation: **Explanation:** **Pemphigus vulgaris (PV)** is the most common variant of the pemphigus group of autoimmune blistering diseases, accounting for approximately **70% of all cases**. It is characterized by the formation of flaccid, intraepidermal blisters on the skin and mucous membranes. The underlying pathophysiology involves IgG autoantibodies directed against **Desmoglein 3** (primarily mucosal) and **Desmoglein 1** (skin), leading to loss of cell-to-cell adhesion (acantholysis) in the suprabasal layer. **Analysis of Options:** * **Pemphigus vegetans (B):** A rare clinical variant of PV characterized by vegetative plaques in intertriginous areas (axilla/groin). It is not the most common form. * **Pemphigus foliaceus (C):** The second most common variant. It is more superficial than PV because antibodies target only **Desmoglein 1**. Blisters are so fragile they are rarely seen; patients present with "cornflake" scales. * **Pemphigus erythematosus (D):** Also known as Senear-Usher syndrome, this is a localized variant of pemphigus foliaceus with features of Lupus Erythematosus. It is relatively rare. **High-Yield NEET-PG Pearls:** * **Site of Cleavage:** Suprabasal (PV) vs. Subcorneal (PF). * **Tzanck Smear:** Shows **Acantholytic cells** (Tzanck cells/Row of tombstone appearance). * **Nikolsky Sign:** Characteristically **positive** in all forms of Pemphigus. * **Immunofluorescence (DIF):** Shows a **"Fish-net"** or "Lace-like" pattern of IgG/C3 deposits. * **Clinical Tip:** PV almost always starts with **oral ulcers** before progressing to skin involvement.

Question 79: Linear band of immunofluorescence (due to immunoglobulin deposition) along the dermoepidermal junction (Ribbon candy pattern) is seen in which of the following conditions?

A. Bullous pemphigoid (Correct Answer)
B. Dermatitis herpetiformis
C. Pemphigus vulgaris
D. Lichen planus

Explanation: **Explanation:** The correct answer is **Bullous pemphigoid (BP)**. This condition is characterized by the production of autoantibodies (IgG) against the hemidesmosomal proteins **BP180 (BPAG2)** and **BP230 (BPAG1)** at the dermoepidermal junction (DEJ). On Direct Immunofluorescence (DIF), this results in a continuous, smooth, **linear band of IgG and C3** along the basement membrane zone, often described as a **"Ribbon candy"** or "tubular" pattern. **Analysis of Options:** * **Dermatitis herpetiformis:** Shows **granular** IgA deposits specifically at the tips of the dermal papillae, not a linear band. It is associated with Celiac disease. * **Pemphigus vulgaris:** Involves antibodies against Desmoglein 3 (and 1). DIF shows a **"fishnet" or "lace-like"** pattern of IgG/C3 within the epidermis (intercellular), not at the DEJ. * **Lichen planus:** Characterized by **shaggy** linear fibrinogen deposition at the DEJ and the presence of Civatte bodies (cytoid bodies) that stain with IgM. **High-Yield Clinical Pearls for NEET-PG:** * **Target Antigens:** BP180 (transmembrane) is the primary pathogenic target in Bullous Pemphigoid. * **Clinical Feature:** Tense bullae on an erythematous base (unlike the flaccid bullae of Pemphigus) that do not rupture easily. * **Histopathology:** Subepidermal blister with an inflammatory infiltrate rich in **eosinophils**. * **Nikolsky Sign:** Negative in Bullous Pemphigoid (Positive in Pemphigus).

Question 80: A 15-year-old girl complains of itchy skin lesions of 6 months in duration. Physical examination reveals numerous wheal-like lesions with small vesicles over her elbows and knees. A skin biopsy demonstrates inflammation in the tips of the dermal papillae and subepidermal vesicles. Which of the following histopathologic findings would provide the best evidence to support a diagnosis of dermatitis herpetiformis in this patient?

A. Horn and pseudo-horn cysts
B. IgA deposits in dermal papillae (Correct Answer)
C. Koilocytotic change
D. Microabscesses in the stratum corneum

Explanation: ### Explanation **Dermatitis Herpetiformis (DH)** is a chronic, intensely pruritic autoimmune blistering disease strongly associated with **Gluten-Sensitive Enteropathy (Celiac Disease)**. **1. Why the Correct Answer is Right:** The hallmark of DH is the presence of **granular IgA deposits** localized at the **tips of the dermal papillae** (detected via Direct Immunofluorescence/DIF). Pathophysiologically, IgA antibodies against tissue transglutaminase (tTG-2) cross-react with epidermal transglutaminase (eTG-3) in the skin. These deposits trigger the recruitment of neutrophils, leading to the formation of **neutrophilic microabscesses** at the papillary tips, which eventually cause subepidermal clefting. **2. Analysis of Incorrect Options:** * **A. Horn and pseudo-horn cysts:** These are characteristic histopathological features of **Seborrheic Keratosis**, representing keratin-filled epidermal invaginations. * **C. Koilocytotic change:** This refers to cells with perinuclear halos and wrinkled nuclei, indicative of Human Papillomavirus (HPV) infection, typically seen in **Viral Warts**. * **D. Microabscesses in the stratum corneum:** Known as **Munro’s microabscesses**, these are collections of neutrophils in the upper epidermis characteristic of **Psoriasis**, not subepidermal blistering diseases. **3. Clinical Pearls for NEET-PG:** * **Classic Presentation:** Symmetrical, extremely itchy vesicles/wheals on **extensor surfaces** (elbows, knees, buttocks). * **Histology:** Subepidermal blister with **neutrophilic papillary microabscesses**. * **DIF (Gold Standard):** Granular IgA deposits in dermal papillae. * **Treatment of Choice:** **Dapsone** (provides rapid relief of itch) + Strict **Gluten-free diet** (long-term management). * **Association:** HLA-DQ2 and HLA-DQ8.

Practice by Chapter

Pemphigus Vulgaris

Practice Questions

Pemphigus Foliaceus

Practice Questions

Bullous Pemphigoid

Practice Questions

Cicatricial Pemphigoid

Practice Questions

Dermatitis Herpetiformis

Practice Questions

Epidermolysis Bullosa

Practice Questions

Linear IgA Bullous Dermatosis

Practice Questions

Pemphigoid Gestationis

Practice Questions

Drug-Induced Bullous Disorders

Practice Questions

Immunofluorescence in Bullous Diseases

Practice Questions

Management of Autoimmune Bullous Diseases

Practice Questions

Genetic Counseling in Inherited Blistering Diseases

Practice Questions

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