Blistering Diseases — MCQs

Blistering Diseases Indian Medical PG Practice Questions and MCQs

Question 21: Blistering in Bullous pemphigoid is because of antibodies against which of the following antigens?

A. BPAG2 (Correct Answer)
B. BPAG1
C. Filaggrin
D. Keratin 5

Explanation: **Explanation:** **Bullous Pemphigoid (BP)** is an autoimmune subepidermal blistering disorder primarily affecting the elderly. The pathogenesis involves the formation of IgG autoantibodies against components of the **hemidesmosome**, which anchors the basal layer of the epidermis to the basement membrane. 1. **Why BPAG2 is correct:** The primary pathogenic target in BP is **BPAG2 (Bullous Pemphigoid Antigen 2)**, also known as **Type XVII Collagen**. It is a transmembrane protein. Antibodies against the extracellular **NC16A domain** of BPAG2 are responsible for the subepidermal split and blister formation. 2. **Why other options are incorrect:** * **BPAG1 (BP230):** This is an intracellular plakin family protein. While antibodies to BPAG1 are found in BP, they are generally considered secondary and less pathogenic than anti-BPAG2. * **Filaggrin:** This protein aggregates keratin filaments in the stratum corneum. Mutations in the filaggrin gene (*FLG*) are associated with **Ichthyosis vulgaris** and **Atopic Dermatitis**, not blistering diseases. * **Keratin 5:** Mutations in Keratin 5 (and Keratin 14) lead to **Epidermolysis Bullosa Simplex**, where blistering occurs due to mechanical fragility within the basal layer. **High-Yield Clinical Pearls for NEET-PG:** * **Immunofluorescence:** Direct Immunofluorescence (DIF) shows **linear IgG and C3 deposits** along the basement membrane zone. * **Clinical Feature:** Characterized by **tense bullae** on an erythematous base, often preceded by a chronic pruritic eczematous phase. * **Histopathology:** Subepidermal blister with a prominent **eosinophilic** infiltrate. * **Mnemonic:** **B**ullous = **B**elow (Subepidermal) and **B**PAG**2** (Transmembrane/Pathogenic).

Question 22: Target lesions are observed in which of the following conditions?

A. Erythema multiforme (Correct Answer)
B. Lichen planus
C. Pemphigus vulgaris
D. Psoriasis

Explanation: **Explanation:** **Erythema Multiforme (EM)** is the classic condition associated with **target (iris) lesions**. These are pathognomonic, concentric inflammatory rings typically found on the palms, soles, and extensor surfaces. A "typical" target lesion consists of three distinct zones: a dusky/blistering central disc, a pale edematous intermediate ring, and an erythematous outer halo. This hypersensitivity reaction is most commonly triggered by **Herpes Simplex Virus (HSV)** or certain medications (e.g., sulfonamides, NSAIDs). **Why other options are incorrect:** * **Lichen Planus:** Characterized by the "6 Ps" (Planar, Purple, Polygonal, Pruritic, Papules, and Plaques). It features **Wickham striae** (whitish reticular lines) rather than target lesions. * **Pemphigus Vulgaris:** An autoimmune blistering disease characterized by flaccid bullae and a positive **Nikolsky sign**. It involves intraepidermal acantholysis but does not present with targetoid morphology. * **Psoriasis:** Presents as well-demarcated erythematous plaques with silvery-white scales. Key clinical signs include the **Auspitz sign** and **Grattage test**, not target lesions. **NEET-PG High-Yield Pearls:** * **Typical vs. Atypical:** Typical target lesions (3 zones) are seen in EM; atypical target lesions (2 zones) are more common in Stevens-Johnson Syndrome (SJS). * **Most common trigger:** HSV-1 is the most frequent precipitant for EM Minor. * **Histology:** Look for "satellite cell necrosis" (individual necrotic keratinocytes surrounded by lymphocytes). * **Differential:** Targetoid lesions can occasionally be seen in Urticaria, but they are transient (lasting <24 hours), whereas EM lesions are fixed for several days.

Question 23: Subepithelial vesicles are characteristic of all of the following conditions EXCEPT?

A. Bullous pemphigoid
B. Cicatricial pemphigoid
C. Pemphigus (Correct Answer)
D. Epidermolysis bullosa acquisita

Explanation: **Explanation:** The level of blister formation is the most critical diagnostic feature in immunobullous disorders. Blisters are classified as either **intraepidermal** (within the epidermis) or **subepidermal** (below the epidermis/dermo-epidermal junction). **Why Pemphigus is the Correct Answer:** Pemphigus (including Pemphigus Vulgaris and Pemphigus Foliaceus) is characterized by **intraepidermal** vesicles. This occurs due to **acantholysis**—the loss of intercellular connections (desmosomes) between keratinocytes caused by IgG antibodies against Desmogleins. Because the split occurs within the cellular layer, the resulting blisters are thin-walled, flaccid, and rupture easily (positive Nikolsky sign). **Analysis of Incorrect Options (Subepithelial/Subepidermal Conditions):** All other options involve pathology at the dermo-epidermal junction (DEJ), leading to a split below the epithelium: * **Bullous Pemphigoid:** Caused by antibodies against BP180 and BP230 in the hemidesmosomes. The split is subepidermal, resulting in tense bullae. * **Cicatricial Pemphigoid (Mucous Membrane Pemphigoid):** A subepithelial blistering disease primarily affecting mucous membranes, often leading to scarring. * **Epidermolysis Bullosa Acquisita (EBA):** Characterized by antibodies against Type VII collagen in the anchoring fibrils, located below the lamina densa (subepithelial). **High-Yield Clinical Pearls for NEET-PG:** * **Nikolsky Sign:** Positive in Pemphigus (intraepidermal); Negative in Bullous Pemphigoid (subepidermal). * **Tzanck Smear:** Shows "Acantholytic cells" (Tzanck cells) in Pemphigus; absent in subepidermal diseases. * **Dermatitis Herpetiformis:** Another high-yield subepidermal condition associated with Celiac disease and IgA deposits in dermal papillae. * **Mnemonic:** "Pemphig**u**s is **U**p" (Intraepidermal); "Pemphigoi**d** is **D**eep" (Subepidermal).

Question 24: A young boy presents with multiple flaccid bullous lesions over the trunk with some oral mucosal lesions. What is the most likely finding on immunofluorescence study of the biopsy specimen?

A. 'Fishnet' IgG deposits in epidermis (Correct Answer)
B. Linear IgG deposits
C. Linear IgA in dermal papillae
D. Granular IgA in reticular dermis

Explanation: The clinical presentation of **flaccid bullae** on the trunk and **oral mucosal involvement** in a young patient is characteristic of **Pemphigus Vulgaris (PV)**. ### **Explanation of the Correct Answer** In Pemphigus Vulgaris, autoantibodies (IgG) are directed against **Desmoglein 3** (and Desmoglein 1), which are components of desmosomes. This leads to **acantholysis** (loss of cell-to-cell adhesion). On Direct Immunofluorescence (DIF), these IgG antibodies deposit in the intercellular spaces between keratinocytes throughout the epidermis, creating a characteristic **'Fishnet' or 'Chicken-wire' appearance**. ### **Why Other Options are Incorrect** * **B. Linear IgG deposits:** This is the hallmark of **Bullous Pemphigoid**, where antibodies target the basement membrane zone (BP180/230). Clinically, it presents with *tense* bullae and rarely involves the mucosa. * **C. Linear IgA in dermal papillae:** This is seen in **Linear IgA Bullous Dermatosis (LABD)**. It typically presents with a "string of beads" appearance of vesicles. * **D. Granular IgA in reticular dermis:** This is characteristic of **Dermatitis Herpetiformis**, which is associated with Celiac disease. The deposits are specifically found at the **tips of dermal papillae**, not the reticular dermis. ### **High-Yield NEET-PG Pearls** * **Nikolsky Sign:** Positive in Pemphigus Vulgaris (due to acantholysis) but negative in Bullous Pemphigoid. * **Tzanck Smear:** Shows **Acantholytic cells (Tzanck cells)**—large, round keratinocytes with hyperchromatic nuclei. * **Histopathology:** Shows "Row of Tombstones" appearance (basal layer remains attached to the basement membrane). * **Target Antigens:** PV (Desmoglein 3 > 1); Pemphigus Foliaceus (Desmoglein 1 only; no mucosal involvement).

Question 25: All of the following are immunologically mediated blistering diseases except?

A. Pemphigus vulgaris
B. Pemphigus foliaceous
C. Bullous pemphigoid
D. Psoriasis (Correct Answer)

Explanation: ### Explanation The core concept tested here is the distinction between **immunobullous (autoimmune)** diseases and **chronic inflammatory** skin conditions. **Why Psoriasis is the Correct Answer:** Psoriasis is a chronic, T-cell mediated inflammatory disease characterized by epidermal hyperplasia (acanthosis) and accelerated keratinocyte turnover. While it involves the immune system, it is **not** an immunobullous disease. It typically presents with well-demarcated erythematous plaques with silvery scales, not primary blisters. Histologically, it shows Munro’s microabscesses and Kogoj’s pustules, but no autoantibodies against dermo-epidermal adhesion molecules. **Why the other options are incorrect:** * **Pemphigus Vulgaris (A) & Pemphigus Foliaceous (B):** These are classic intraepidermal immunobullous diseases caused by IgG autoantibodies against **Desmogleins** (Dsg3 and Dsg1). This leads to **acantholysis** (loss of cell-to-cell adhesion). * **Bullous Pemphigoid (C):** This is a subepidermal immunobullous disease caused by autoantibodies against **BP180 and BP230** (hemidesmosomes) at the dermo-epidermal junction. **NEET-PG High-Yield Clinical Pearls:** 1. **Nikolsky Sign:** Positive in Pemphigus (intraepidermal) and negative in Bullous Pemphigoid (subepidermal). 2. **Direct Immunofluorescence (DIF):** * *Pemphigus:* "Fish-net" or "Lace-like" pattern. * *Bullous Pemphigoid:* Linear IgG and C3 along the basement membrane zone. 3. **Tzanck Smear:** Shows **Acantholytic cells** (Tzanck cells) in Pemphigus, but not in Psoriasis or Bullous Pemphigoid. 4. **Psoriasis Trigger:** Often associated with the **Auspitz sign** (pinpoint bleeding upon scale removal) and **Koebner phenomenon**.

Question 26: Which condition is characterized by oral, ocular, and genital lesions?

A. Erythema multiforme
B. Stevens-Johnson syndrome (Correct Answer)
C. Systemic lupus erythematosus
D. None of the above

Explanation: **Explanation:** **Stevens-Johnson Syndrome (SJS)** is a severe mucocutaneous reaction, typically triggered by drugs (e.g., sulfonamides, anticonvulsants, NSAIDs). It is characterized by extensive keratinocyte apoptosis leading to skin detachment. A hallmark of SJS is the involvement of **at least two mucosal surfaces**. The classic triad involves **oral** (hemorrhagic crusting of lips/stomatitis), **ocular** (purulent conjunctivitis), and **genital** (balanitis/vulvovaginitis) lesions, accompanied by targetoid macules and skin sloughing (<10% body surface area). **Analysis of Options:** * **Erythema Multiforme (EM):** While EM can involve mucosa (EM Major), it is primarily characterized by "target" or "iris" lesions on the extremities. It is usually triggered by infections (HSV) rather than drugs and is clinically distinct from the SJS/TEN spectrum. * **Systemic Lupus Erythematosus (SLE):** SLE commonly presents with oral ulcers (usually painless) and a malar rash, but it does not typically present with the acute, widespread, multi-mucosal blistering and sloughing seen in SJS. * **None of the above:** Incorrect, as SJS fits the clinical description perfectly. **High-Yield Clinical Pearls for NEET-PG:** * **SJS vs. TEN:** SJS involves <10% BSA; TEN involves >30% BSA; 10-30% is the SJS/TEN overlap. * **Nikolsky Sign:** Positive in SJS/TEN (lateral pressure causes skin detachment). * **Histopathology:** Shows **subepidermal bullae** with full-thickness epidermal necrosis. * **SCORTEN:** The prognostic scoring system used to predict mortality in SJS/TEN patients. * **Most common cause:** Drugs (Sulfonamides are the most frequent triggers).

Question 27: Which one of the following is the treatment of choice for Dermatitis Herpetiformis?

A. Corticosteroids
B. Dapsone (Correct Answer)
C. Methotrexate
D. Retinoids

Explanation: **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 is the **drug of choice** for DH because it inhibits the migration and function of neutrophils. In DH, IgA antibodies deposit at the tips of dermal papillae, leading to the recruitment of neutrophils and subsequent blister formation. Dapsone provides dramatic relief, often stopping the intense itching and preventing new lesion formation within 24 to 48 hours. However, while Dapsone treats the skin symptoms, it does not address the underlying enteropathy. **Why Other Options are Incorrect:** * **Corticosteroids:** While useful in other immunobullous diseases like Pemphigus Vulgaris, they are generally ineffective as a primary treatment for DH. * **Methotrexate:** This is an immunosuppressant used in psoriasis or severe eczema but has no specific role in the management of DH. * **Retinoids:** These are used for keratinization disorders (e.g., Acne, Psoriasis) and are not indicated for DH. **NEET-PG High-Yield Pearls:** * **Gold Standard Management:** A lifelong **Gluten-Free Diet (GFD)** is the only treatment that addresses the underlying pathology and reduces the risk of GI lymphoma. * **Histopathology:** Shows subepidermal blisters with **"Microabscesses"** at the dermal papillary tips (neutrophilic infiltrate). * **Direct Immunofluorescence (DIF):** The hallmark is **granular IgA deposits** in the dermal papillae. * **Associated HLA:** Strongly associated with **HLA-DQ2** and **HLA-DQ8**. * **Dapsone Pre-requisite:** Always check **G6PD levels** before starting Dapsone to avoid drug-induced hemolytic anemia.

Question 28: A 60-year-old man presented with itchy tense blisters on normal-looking skin and urticarial rash. What is the primary investigation for the diagnosis?

A. Direct immunofluorescence (Correct Answer)
B. Indirect immunofluorescence
C. Histopathology
D. Cytopathology

Explanation: **Explanation:** The clinical presentation of **tense blisters** on a 60-year-old patient, associated with an **urticarial rash** and intense itching, is classic for **Bullous Pemphigoid (BP)**. In BP, the split occurs at the subepidermal level (basement membrane zone), leading to strong, tense roofs that do not rupture easily. **Why Direct Immunofluorescence (DIF) is the Correct Answer:** DIF is the **gold standard** for diagnosing autoimmune blistering diseases. In Bullous Pemphigoid, DIF of perilesional skin typically shows a **linear deposition of IgG and C3 along the basement membrane zone (BMZ)**. This confirms the presence of autoantibodies (anti-BP180 and anti-BP230) bound to the tissue, providing a definitive diagnosis. **Analysis of Incorrect Options:** * **Indirect Immunofluorescence (IIF):** This tests the patient’s **serum** for circulating antibodies. While useful for monitoring disease activity, it is less sensitive than DIF for primary diagnosis. * **Histopathology:** While a biopsy would show a subepidermal cleft with eosinophils, it cannot distinguish BP from other subepidermal diseases (like Epidermolysis Bullosa Acquisita) as reliably as DIF. * **Cytopathology (Tzanck Smear):** This is used to identify acantholytic cells (Tzanck cells) in **Pemphigus Vulgaris** or multinucleated giant cells in Herpes. It is not useful for subepidermal blisters like BP. **High-Yield Clinical Pearls for NEET-PG:** * **Bullous Pemphigoid:** Tense blisters, subepidermal, negative Nikolsky sign, linear IgG/C3 on DIF. * **Pemphigus Vulgaris:** Flaccid blisters, intraepidermal, positive Nikolsky sign, "row of tombstones" on histology, "fishnet/lace-like" pattern on DIF. * **Salt-split skin technique:** A specialized IIF used to differentiate BP (roof pattern) from EBA (floor pattern).

Question 29: Which condition is characterized by mucocutaneous lesions associated with neoplasia?

A. Pemphigus vegetans
B. Parapemphigus
C. Paraneoplastic pemphigus (Correct Answer)
D. Familial benign pemphigus

Explanation: **Explanation:** **Paraneoplastic Pemphigus (PNP)** is the correct answer because it is a distinct autoimmune bullous disease specifically triggered by an underlying neoplasm. The most common associations are hematologic malignancies, particularly **Non-Hodgkin Lymphoma**, Chronic Lymphocytic Leukemia (CLL), and Castleman disease. **Why the correct answer is right:** PNP is characterized by severe, recalcitrant **stomatitis** (painful oral erosions) and polymorphic cutaneous eruptions. Pathophysiologically, it involves antibodies against **Desmogleins (1 and 3)** and **Plakins** (specifically Periplanin and Desmoplakin). This dual targeting leads to both acantholysis (as seen in pemphigus) and interface dermatitis (resembling lichen planus or erythema multiforme). **Why the other options are incorrect:** * **Pemphigus vegetans:** A rare variant of Pemphigus Vulgaris characterized by vegetating plaques in intertriginous areas; it is not typically associated with malignancy. * **Parapemphigus:** Another name for **Bullous Pemphigoid**. While it occurs in the elderly, it is not considered a true paraneoplastic syndrome, though it may occasionally co-exist with systemic cancers. * **Familial benign pemphigus (Hailey-Hailey disease):** A genetic (autosomal dominant) defect in the *ATP2C1* gene affecting calcium transport in keratinocytes. It is a hereditary condition, not a neoplastic one. **High-Yield NEET-PG Pearls:** * **Most common association:** Non-Hodgkin Lymphoma. * **Most common association in children:** Castleman disease. * **Key Diagnostic Feature:** Presence of **Anti-plakin antibodies**. * **Clinical Clue:** Severe mucosal involvement that is often resistant to standard pemphigus treatments. * **Immunofluorescence:** Shows both IgG/C3 in the intercellular spaces (fishnet pattern) and along the basement membrane zone.

Question 30: Level of splitting in epidermolysis bullosa simplex is?

A. Intraepidermal (Correct Answer)
B. Subepidermal
C. Subcorneal
D. None of the above

Explanation: **Explanation:** **Epidermolysis Bullosa Simplex (EBS)** is a group of mechanobullous disorders characterized by skin fragility and blistering following minor mechanical trauma. **1. Why Intraepidermal is Correct:** In EBS, the genetic defect typically involves mutations in **Keratin 5 and Keratin 14**. These keratins form the structural framework of the **basal layer of the epidermis**. Because the structural integrity of these basal cells is compromised, they rupture (cytolysis) upon friction. This results in a split occurring **within the epidermis** (specifically through the basal cell layer), making it an **intraepidermal** blistering disease. **2. Why Other Options are Incorrect:** * **Subepidermal:** This is the level of splitting seen in **Junctional EB** (split at the lamina lucida) and **Dystrophic EB** (split below the lamina densa). It is also characteristic of autoimmune diseases like Bullous Pemphigoid. * **Subcorneal:** This level of splitting occurs just below the stratum corneum, typical of **Pemphigus Foliaceus** or **Impetigo**, where the split is very superficial. **3. Clinical Pearls for NEET-PG:** * **Inheritance:** Most forms of EBS are **Autosomal Dominant**. * **Target Proteins:** Keratin 5 and 14 (High-yield). * **Clinical Feature:** Blisters usually heal **without scarring** or milia (unlike Dystrophic EB) because the basement membrane remains intact. * **Weber-Cockayne Syndrome:** The most common localized variant of EBS, affecting primarily the palms and soles. * **Electron Microscopy:** This is the gold standard for determining the exact level of cleavage in EB subtypes.

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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