Blistering Diseases Practice Questions

Q: All of the following are associated with pemphigus except:

Atrophic gastritis. **Explanation:** Pemphigus is a group of autoimmune blistering diseases characterized by acantholysis (loss of intercellular connections) due to autoantibodies against desmogleins. The question focuses on the clinical associations of **Pemphigus Vulgaris (PV)** and **Paraneoplastic Pemphigus (PNP)**. **Why Atrophic Gastritis is the correct answer:** Atrophic gastritis is an autoimmune condition associated with **Pernicious Anemia** and **Vitiligo**, but it has no established pathophysiological link with Pemphigus. While both are autoimmune, they do not share the same HLA associations or syndromic clusters. **Analysis of Incorrect Options:** * **Thymoma & Myasthenia Gravis (MG):** There is a well-documented "immunological triad" between Thymoma, MG, and Pemphigus Vulgaris. The thymus is responsible for T-cell education; a thymoma can lead to a breakdown in self-tolerance, resulting in the production of autoantibodies against both acetylcholine receptors (MG) and desmogleins (Pemphigus). * **CLL (Chronic Lymphocytic Leukemia):** This is the most common malignancy associated with **Paraneoplastic Pemphigus (PNP)**. PNP is frequently triggered by B-cell lymphoproliferative disorders, including CLL, Non-Hodgkin Lymphoma, and Castleman’s disease. **NEET-PG High-Yield Pearls:** 1. **Most common association of PNP:** Non-Hodgkin Lymphoma (Adults) and Castleman’s Disease (Children). 2. **Drug-induced Pemphigus:** Most commonly caused by **Penicillamine** (thiol group drugs). 3. **HLA Association:** Pemphigus is strongly linked with **HLA-DR4** and **DRw6**. 4. **Clinical Sign:** **Nikolsky sign** is positive in Pemphigus but negative in Bullous Pemphigoid.

Q: Which of the following is NOT a vesiculobullous lesion?

Scabies / Atopic dermatitis. The primary classification of skin lesions depends on their morphology. **Vesiculobullous diseases** are characterized by fluid-filled elevations (vesicles 0.5 cm) as their primary and predominant clinical feature. ### **Why Option B is the Correct Answer** **Scabies** and **Atopic Dermatitis** are primarily characterized by different morphologies. Scabies is a parasitic infestation presenting with **burrows, papules, and nodules** in a characteristic distribution (Circle of Hebra). Atopic Dermatitis is an inflammatory condition presenting with **erythematous plaques, scaling, and lichenification**. While secondary vesiculation can occur (e.g., in acute eczema), they are not classified as primary vesiculobullous disorders. ### **Analysis of Incorrect Options** * **A. Dermatitis Herpetiformis:** A chronic autoimmune subepidermal blistering disease associated with Celiac disease. It presents with intensely pruritic, grouped (herpetiform) vesicles on extensor surfaces. * **C. Pemphigus:** A group of autoimmune diseases (e.g., Pemphigus Vulgaris) characterized by **intraepidermal** blisters due to acantholysis (loss of keratinocyte adhesion). * **D. Pemphigoid:** Specifically Bullous Pemphigoid, which is an autoimmune **subepidermal** blistering disease common in the elderly, characterized by tense bullae. ### **NEET-PG Clinical Pearls** * **Nikolsky Sign:** Positive in Pemphigus (intraepidermal) but negative in Pemphigoid (subepidermal). * **Immunofluorescence (DIF):** * *Pemphigus:* "Fish-net" or "Lace-like" IgG/C3 deposits. * *Bullous Pemphigoid:* Linear IgG/C3 along the basement membrane zone. * *Dermatitis Herpetiformis:* Granular IgA deposits at the dermal papillary tips. * **Tzanck Smear:** Used for rapid diagnosis of Pemphigus (shows Acantholytic/Tzanck cells) and Herpes Simplex (shows Multinucleated Giant Cells).

Q: What is the drug of choice for dermatitis herpetiformis?

Dapsone. **Explanation:** **Dermatitis Herpetiformis (DH)** is a chronic, intensely pruritic autoimmune blistering disease characterized by subepidermal vesicles. It is considered the cutaneous manifestation of **Celiac disease** (Gluten-sensitive enteropathy). **Why Dapsone is the Correct Answer:** Dapsone (diaminodiphenyl sulfone) is the **drug of choice** for DH. It works by inhibiting the chemotaxis and activation of neutrophils, which are the primary cells responsible for the formation of microabscesses at the dermal papillary tips in DH. The clinical response to Dapsone is often dramatic, with itching subsiding within 24–48 hours. However, while Dapsone treats the skin lesions, it does not affect the underlying enteropathy; therefore, a **strict gluten-free diet** is the definitive long-term management. **Why Other Options are Incorrect:** * **Rifampicin:** An antitubercular drug and RNA polymerase inhibitor; it has no role in managing autoimmune blistering diseases. * **Ketoconazole:** An antifungal agent used for dermatophytosis or seborrheic dermatitis; it does not address the neutrophilic inflammation of DH. * **Azithromycin:** A macrolide antibiotic used for bacterial infections; it is ineffective against the autoimmune mechanism of DH. **High-Yield Clinical Pearls for NEET-PG:** * **Pathognomonic Histology:** Neutrophilic microabscesses at the tips of dermal papillae. * **Direct Immunofluorescence (DIF):** Granular IgA deposits in the dermal papillae (Gold Standard for diagnosis). * **Association:** Strongly associated with HLA-DQ2 and HLA-DQ8. * **Dapsone Pre-requisite:** Always check **G6PD levels** before starting Dapsone to prevent drug-induced hemolytic anemia. Monitor for methemoglobinemia and agranulocytosis.

Q: Bullous pemphigoid is characterized by:

Blisters occurring on urticarial skin. **Explanation:** **Bullous Pemphigoid (BP)** is an autoimmune subepidermal blistering disease caused by IgG autoantibodies against **BP180 (Type XVII collagen)** and **BP230** in the hemidesmosomes of the dermo-epidermal junction. 1. **Why Option A is correct:** BP typically presents in elderly patients, often beginning with a **prodromal phase** of intense pruritus and **urticarial (hive-like) plaques**. Tense, large blisters eventually develop on these erythematous, urticarial bases or on normal-appearing skin. Because the split is subepidermal, the "roof" of the blister is the entire epidermis, making it thick and resistant to rupture. 2. **Why other options are incorrect:** * **Option B (Positive Nikolsky sign):** This is characteristic of **Pemphigus Vulgaris** (intraepidermal split). In BP, the Nikolsky sign is **negative** because the adhesion between keratinocytes is intact. * **Option C (Easily rupturing blisters):** This describes **flaccid bullae**, seen in Pemphigus. BP is characterized by **tense bullae** that do not rupture easily. * **Option D (Acantholysis):** This refers to the loss of intercellular connections (desmosomes) between keratinocytes. It is the hallmark of Pemphigus, not BP. **High-Yield Clinical Pearls for NEET-PG:** * **Direct Immunofluorescence (DIF):** Shows **linear** IgG and C3 deposits along the basement membrane zone (BMZ). * **Salt-split skin study:** Fluorescence is seen on the **roof** (epidermal side) of the split. * **Mucosal involvement:** Rare in BP (unlike Pemphigus Vulgaris). * **Treatment:** Potent topical corticosteroids (e.g., Clobetasol) or systemic steroids.

Q: Frenkel's skin test is positive in which of the following conditions?

Toxoplasmosis. **Explanation:** **Correct Answer: B. Toxoplasmosis** **Frenkel’s skin test** (also known as the Toxoplasmin skin test) is a delayed-type hypersensitivity (Type IV) reaction used to detect past or chronic infection with *Toxoplasma gondii*. It involves the intradermal injection of toxoplasmin (an antigen derived from the parasite). A positive result is indicated by induration and erythema at the injection site after 24–48 hours. While largely replaced by serology (ELISA) in modern practice, it remains a classic high-yield fact in medical examinations. **Analysis of Incorrect Options:** * **A. Spinal cord compression:** This is a neurological emergency usually diagnosed via MRI. There is no specific "Frenkel’s skin test" for this; however, "Frenkel’s exercises" are a known rehabilitation technique for ataxia, which may cause confusion. * **C. Pemphigus & D. Pemphigoid:** These are autoimmune blistering diseases. They are diagnosed using the **Nikolsky sign** (positive in Pemphigus), **Tzanck smear** (acantholytic cells in Pemphigus), and **Direct Immunofluorescence (DIF)**. Frenkel's test has no diagnostic value in dermatology for bullous disorders. **High-Yield Clinical Pearls for NEET-PG:** * **Toxoplasmosis Triad (Congenital):** Chorioretinitis, Hydrocephalus, and Intracranial calcifications. * **Other Skin Tests to Remember:** * **Frei’s Test:** Lymphogranuloma Venereum (LGV). * **Mitsuda/Fernandez Test:** Leprosy. * **Cassoni’s Test:** Hydatid disease. * **Montenegro Test:** Leishmaniasis. * **Tzanck Smear:** Used for Pemphigus, Herpes Simplex, and Varicella.

Q: A 60-year-old male presented with large tense bullae on large urticarial plaques, some of which were hemorrhagic. On examination, the bullae did not rupture easily, with the absence of Nikolsky's and bulla spread signs. Some lesions healed with milia formation. A direct immunofluorescence test of a skin biopsy was performed. Which of the following structures is most likely to be involved?

Pemphigus vulgaris. **Explanation:** The clinical presentation described—**large tense bullae** on **urticarial plaques**, absence of **Nikolsky’s sign**, and the presence of **milia**—is characteristic of subepidermal blistering diseases. **Note on the Correct Answer:** While the provided key indicates **Pemphigus Vulgaris (A)**, there appears to be a clinical mismatch. Pemphigus vulgaris typically presents with *flaccid* bullae, positive Nikolsky’s sign, and oral involvement. The description of **tense bullae** and **milia** formation strongly points towards **Epidermolysis Bullosa Acquisita (EBA)** or Bullous Pemphigoid. However, adhering to the provided key: 1. **Pemphigus Vulgaris (A):** Classically involves IgG antibodies against **Desmoglein 3 and 1**. It results in intraepidermal acantholytic blisters. (Note: Clinically, this patient's "tense" bullae and "milia" are atypical for PV). 2. **Bullous Pemphigoid (B):** Features tense bullae on urticarial bases in the elderly. It involves antibodies against **BP180/BP230** at the hemidesmosomes. While it fits the "tense bullae" description, milia are rare. 3. **Epidermolysis Bullosa Acquisita (C):** This is the most likely clinical diagnosis for the description provided. It involves antibodies against **Type VII Collagen**. It is characterized by mechanobullous lesions that heal with **milia** and scarring. 4. **Dermatitis Herpetiformis (D):** Presents as intensely pruritic, grouped vesicles on an erythematous base (extensor surfaces), associated with Celiac disease. **NEET-PG High-Yield Pearls:** * **Tense Bullae:** Subepidermal (BP, EBA, Cicatricial Pemphigoid). * **Flaccid Bullae:** Intraepidermal (Pemphigus group). * **Milia Formation:** Suggests a deep (subepidermal) blister with scarring, most commonly seen in **EBA** and Porphyria Cutanea Tarda. * **Nikolsky Sign:** Positive in Pemphigus; Negative in Bullous Pemphigoid.

Q: Desmoglein is an autoantigen in which of the following conditions?

Pemphigus. **Explanation:** The correct answer is **Pemphigus**. This group of autoimmune blistering diseases is characterized by the production of IgG autoantibodies against **Desmogleins (Dsg)**, which are calcium-dependent cell adhesion molecules (cadherins) found in **desmosomes**. Desmosomes are responsible for holding adjacent keratinocytes together. When these are targeted, it leads to **acantholysis** (loss of cell-to-cell adhesion), resulting in the formation of intraepidermal blisters. * **Pemphigus Vulgaris:** Autoantibodies against **Dsg3** (mucosal-dominant) or **Dsg1 and Dsg3** (mucocutaneous). * **Pemphigus Foliaceus:** Autoantibodies against **Dsg1** only (superficial blisters). **Why other options are incorrect:** * **Eczema (Dermatitis):** This is an inflammatory response characterized by spongiosis (intercellular edema) in the epidermis, not an autoimmune attack on desmogleins. * **Sarcoidosis:** A multisystem granulomatous disease characterized by non-caseating epithelioid granulomas. * **Vitiligo:** An autoimmune destruction of **melanocytes**, leading to depigmented patches, unrelated to desmosomal proteins. **High-Yield Clinical Pearls for NEET-PG:** * **Nikolsky Sign:** Positive in Pemphigus (denotes active acantholysis). * **Tzanck Smear:** Shows **Acantholytic cells** (Tzanck cells)—large, round keratinocytes with hyperchromatic nuclei. * **Direct Immunofluorescence (DIF):** Shows a characteristic **"Fishnet" or "Lace-like" pattern** of IgG and C3 deposits in the intercellular spaces. * **Bullous Pemphigoid (Differential):** Targets **BP180 and BP230** (Hemidesmosomes), leading to subepidermal blisters and a negative Nikolsky sign.

Q: What is the drug of choice in dermatitis herpetiformis?

Dapsone. ### Explanation **Dermatitis Herpetiformis (DH)** is a chronic, intensely pruritic autoimmune blistering disease strongly associated with **Gluten-Sensitive Enteropathy (Celiac Disease)**. It is characterized by subepidermal blisters and the deposition of granular IgA at the dermal papillae tips. **Why Dapsone is the Correct Answer:** Dapsone (diaminodiphenyl sulfone) is the **drug of choice** for DH. Its primary mechanism involves inhibiting the migration of neutrophils to the site of inflammation and suppressing the release of lysosomal enzymes. In DH, the response to Dapsone is often dramatic, with itching and burning sensations subsiding within 24–48 hours. However, while Dapsone controls the skin manifestations, it does not treat the underlying bowel pathology. **Analysis of Incorrect Options:** * **A. Corticosteroids:** While used in many autoimmune bullous diseases (like Pemphigus), they are generally ineffective as monotherapy for DH and are not the primary treatment. * **B. Colchicine:** Sometimes used as a second-line agent in neutrophilic dermatoses, but it is far less effective than Dapsone for DH. * **C. Chloroquine:** Used primarily for Malaria and Lupus Erythematosus; it has no role in the management of DH. **High-Yield Clinical Pearls for NEET-PG:** * **Gold Standard Treatment:** Gluten-free diet (long-term) + Dapsone (symptomatic control). * **Histopathology:** Subepidermal blister with **neutrophilic microabscesses** at the dermal papillae tips. * **Direct Immunofluorescence (DIF):** Granular IgA deposits in the dermal papillae (Pathognomonic). * **Dapsone Pre-requisite:** Always check **G6PD levels** before starting Dapsone to avoid drug-induced hemolytic anemia. * **Common Association:** HLA-DQ2 and HLA-DQ8.

Q: Intraepidermal IgG deposition is seen in which condition?

Pemphigus. **Explanation:** The correct answer is **Pemphigus**. This group of autoimmune blistering diseases is characterized by the presence of IgG autoantibodies directed against **desmogleins** (desmoglein 1 and 3), which are proteins responsible for cell-to-cell adhesion in the epidermis. 1. **Why Pemphigus is correct:** In Pemphigus (specifically Pemphigus Vulgaris and Pemphigus Foliaceus), Direct Immunofluorescence (DIF) reveals a characteristic **"fishnet" or "lace-like" pattern** of IgG and C3 deposition. This occurs **intraepidermally** because the target antigens are located on the surface of keratinocytes. This leads to acantholysis (loss of intercellular connections), resulting in intraepidermal blisters. 2. **Why other options are incorrect:** * **Bullous Pemphigoid:** This is a subepidermal blistering disease. IgG and C3 deposition occurs in a **linear pattern along the basement membrane zone (BMZ)**, not within the epidermis. * **Herpes Genitalis:** This is a viral infection caused by HSV-2. While it causes vesicles, the pathology is due to viral cytopathic effects (like multinucleated giant cells on Tzanck smear), not autoimmune IgG deposition. **High-Yield Clinical Pearls for NEET-PG:** * **Pemphigus Vulgaris:** Most common type; involves oral mucosa; Nikolsky sign is positive; Tzanck smear shows **Acantholytic (Tzanck) cells**. * **Bullous Pemphigoid:** Usually affects the elderly; tense bullae; Nikolsky sign is negative; target antigens are BP180 and BP230. * **Dermatitis Herpetiformis:** Associated with Celiac disease; shows **granular IgA deposition** in dermal papillae.

Question 1

All of the following are associated with pemphigus except:

Accepted Answer

Atrophic gastritis

Answer

Thymoma

Answer

CLL (Chronic Lymphocytic Leukemia)

Answer

Myasthenia gravis

Question 2

Which of the following is NOT a vesiculobullous lesion?

Accepted Answer

Scabies / Atopic dermatitis

Answer

Dermatitis Herpetiformis

Answer

Pemphigus

Answer

Pemphigoid

Question 3

What is the drug of choice for dermatitis herpetiformis?

Accepted Answer

Dapsone

Answer

Rifampicin

Answer

Ketoconazole

Answer

Azithromycin

Question 4

Bullous pemphigoid is characterized by:

Accepted Answer

Blisters occurring on urticarial skin

Answer

A positive Nikolsky sign

Answer

Easily rupturing blisters

Answer

Acantholysis

Question 5

Frenkel's skin test is positive in which of the following conditions?

Accepted Answer

Toxoplasmosis

Answer

Spinal cord compression

Answer

Pemphigus

Answer

Pemphigoid

Question 6

A 60-year-old male presented with large tense bullae on large urticarial plaques, some of which were hemorrhagic. On examination, the bullae did not rupture easily, with the absence of Nikolsky's and bulla spread signs. Some lesions healed with milia formation. A direct immunofluorescence test of a skin biopsy was performed. Which of the following structures is most likely to be involved?

Accepted Answer

Pemphigus vulgaris

Answer

Bullous pemphigoid

Answer

Epidermolysis bullosa acquisita

Answer

Dermatitis herpetiformis

Question 7

Desmoglein is an autoantigen in which of the following conditions?

Accepted Answer

Pemphigus

Answer

Eczema

Answer

Sarcoidosis

Answer

Vitiligo

Question 8

Examination of a 2-day-old neonate reveals numerous blisters on the trunk and extremities. Skin biopsy discloses separation of the basal layer of the epidermis from its basement membrane and is devoid of inflammatory cells. No antibody deposits are identified by immunofluorescence microscopy. Which of the following is the most likely diagnosis?

Accepted Answer

Epidermolysis bullosa

Answer

Bullous pemphigoid

Answer

Dermatitis herpetiformis

Answer

Ichthyosis vulgaris

Question 9

What is the drug of choice in dermatitis herpetiformis?

Accepted Answer

Dapsone

Answer

Corticosteroids

Answer

Colchicine

Answer

Chloroquine

Question 10

Intraepidermal IgG deposition is seen in which condition?

Accepted Answer

Pemphigus

Answer

Bullous pemphigoid

Answer

Herpes genitalis

Answer

None of the above

Blistering Diseases — MCQs

Blistering Diseases — MCQs

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