Blistering Diseases Practice Questions

Q: Defects in which of the following does NOT cause blistering?

Filaggrin. **Explanation:** Blistering (bullous) diseases occur due to defects in structural proteins that maintain cell-to-cell adhesion (desmosomes) or cell-to-basement membrane adhesion (hemidesmosomes). **Why Filaggrin is the Correct Answer:** **Filaggrin** (Filament Aggregating Protein) is not a structural adhesion molecule. Its primary role is to aggregate keratin filaments into tight bundles to form the cornified envelope and maintain the skin barrier. Mutations in the *FLG* gene lead to **Ichthyosis vulgaris** and **Atopic dermatitis**, which are characterized by dry, scaly skin and barrier dysfunction, **not** blistering. **Why the other options are incorrect:** * **Collagen VII and Pectin:** Collagen VII forms anchoring fibrils; its defect causes **Dystrophic Epidermolysis Bullosa (DEB)**. Plectin (often grouped with pectin in clinical shorthand) is a plaque protein in hemidesmosomes; its defect causes **EB with Muscular Dystrophy**. * **Laminin:** Laminin-332 is a key component of the lamina lucida. Defects lead to **Junctional Epidermolysis Bullosa (JEB)**, a severe blistering condition. * **Keratin:** Keratins 5 and 14 provide structural integrity to basal keratinocytes. Mutations cause **Epidermolysis Bullosa Simplex (EBS)**, where cells rupture easily, leading to intraepidermal blisters. **NEET-PG High-Yield Pearls:** * **EBS:** Defect in Keratin 5, 14 (Basal layer). * **JEB:** Defect in Laminin-332 (Lamina lucida). * **DEB:** Defect in Collagen VII (Anchoring fibrils). * **Pemphigus Vulgaris:** IgG against Desmoglein 3 (and 1). * **Bullous Pemphigoid:** IgG against BP180 (Collagen XVII) and BP230.

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: Which condition is characterized by severe bullous erythema multiforme with oral, ocular, and genital lesions?

Stevens-Johnson syndrome. **Explanation:** **Stevens-Johnson Syndrome (SJS)** is a severe, immune-mediated mucocutaneous reaction, most commonly triggered by drugs (e.g., sulfonamides, anticonvulsants, NSAIDs). It is characterized by the sudden onset of high fever, malaise, and widespread **bullous erythema multiforme-like lesions** (atypical target lesions). The hallmark of SJS is the involvement of at least **two or more mucosal surfaces**, typically the oral cavity (hemorrhagic crusting of lips), ocular (conjunctivitis/ulceration), and genital mucosa. Pathologically, it involves extensive keratinocyte apoptosis leading to epidermal detachment of **<10% of the total body surface area (BSA)**. **Why other options are incorrect:** * **Darier’s Disease:** An autosomal dominant genodermatosis (ATP2A2 mutation) characterized by greasy, keratotic papules in seborrheic areas and nail changes (V-shaped nicking). It is not an acute bullous or mucosal syndrome. * **Reiter Syndrome (Reactive Arthritis):** Characterized by the triad of urethritis, arthritis, and conjunctivitis ("Can't see, can't pee, can't climb a tree"). While it involves mucosa, the skin lesions are typically *keratoderma blennorrhagica* (psoriasiform lesions on palms/soles), not bullous erythema multiforme. **High-Yield NEET-PG Pearls:** * **SJS vs. TEN:** SJS involves 30% BSA; 10-30% is the SJS/TEN overlap. * **Nikolsky Sign:** Positive in SJS/TEN (epidermal detachment with lateral pressure). * **Most common cause:** Drugs are the primary trigger (Sulfonamides are the most frequent culprits). * **Histopathology:** Shows subepidermal bullae with full-thickness epidermal necrosis.

Q: A 60-year-old patient presented with several bullous lesions for the last 3 days; each bulla was surrounded by an erythematous halo. There were multiple target lesions and oral erosions. What is the most likely diagnosis?

Stevens-Johnson syndrome. **Explanation:** The clinical presentation of **bullous lesions with erythematous halos**, **targetoid lesions**, and **mucosal involvement (oral erosions)** in an adult is classic for **Stevens-Johnson Syndrome (SJS)**. SJS is a severe mucocutaneous hypersensitivity reaction, most commonly triggered by drugs (e.g., sulfonamides, anticonvulsants, NSAIDs). The "target lesions" in SJS are typically "atypical" (two zones) compared to the "classic" targets (three zones) seen in Erythema Multiforme. **Why the other options are incorrect:** * **Chickenpox (Varicella):** Characterized by a pleomorphic rash (macules, papules, and vesicles in different stages) described as "dewdrops on a rose petal." It lacks target lesions and extensive bullae. * **Herpes Simplex:** Usually presents as localized, grouped vesicles on an erythematous base (e.g., cold sores). While it can trigger Erythema Multiforme, the primary infection itself does not present with generalized bullae and targetoid lesions. * **Herpes Zoster:** Presents as painful, unilateral vesicles following a specific dermatomal distribution. It does not cause generalized target lesions or widespread bullae. **Clinical Pearls for NEET-PG:** * **SJS vs. TEN:** The distinction is based on the Body Surface Area (BSA) of epidermal detachment: **SJS 30%**. * **Nikolsky Sign:** Usually positive in SJS/TEN (epidermal shearing with lateral pressure). * **Histology:** Shows full-thickness epidermal necrosis and subepidermal clefting. * **Common Triggers:** Remember the mnemonic **SATAN** (Sulfa drugs, Allopurinol, Tetracyclines, Anticonvulsants, NSAIDs).

Q: Intraepidermal bullae formation occurs in which of the following conditions?

Pemphigus vulgaris. **Explanation:** The level of split (cleavage) within the skin layers is the fundamental diagnostic feature in blistering diseases. **1. Why Pemphigus Vulgaris is Correct:** Pemphigus vulgaris is the prototype of **intraepidermal** blistering. It is an autoimmune disease where IgG antibodies target **Desmoglein 3** (and sometimes Desmoglein 1), which are components of desmosomes. The loss of cell-to-cell adhesion between keratinocytes is called **acantholysis**, leading to the formation of a "suprabasal" split. Because the roof of the blister is thin epidermis, these bullae are typically flaccid and rupture easily. **2. Why the other options are incorrect:** * **Bullous Impetigo:** While this also involves an intraepidermal split (specifically subcorneal), it is caused by staphylococcal exfoliative toxins targeting Desmoglein 1. However, in the context of classic "blistering diseases" exams, Pemphigus is the primary intraepidermal representative. * **Bullous Pemphigoid:** This is a **subepidermal** blistering disease. Antibodies target BP180 and BP230 in the hemidesmosomes at the dermo-epidermal junction. These blisters are tense and do not rupture easily. * **Dermatitis Herpetiformis:** This is also a **subepidermal** condition associated with Celiac disease. It is characterized by IgA deposits in the dermal papillae tips, leading to "micro-abscesses" and subepidermal clefting. **High-Yield Clinical Pearls for NEET-PG:** * **Nikolsky Sign:** Positive in Pemphigus (intraepidermal) and negative in Bullous Pemphigoid (subepidermal). * **Tzanck Smear:** Shows "Acantholytic cells" (Tzanck cells) in Pemphigus. * **Row of Tombstones:** The characteristic histopathological appearance of the basal layer in Pemphigus Vulgaris. * **Direct Immunofluorescence (DIF):** "Fish-net" or "Lace-like" pattern in Pemphigus; "Linear" pattern at the basement membrane in Bullous Pemphigoid.

Q: A twenty-one-year-old woman complains that regular, gentle brushing of her teeth is painful and causes profuse bleeding. Oral examination reveals the loss of epithelium from the attached gingiva of both arches. Which of the following dermatological problems is this patient most likely to have?

Benign mucous membrane pemphigoid. The clinical presentation of painful, bleeding gums with loss of epithelium from the attached gingiva is the classic description of **Desquamative Gingivitis**. ### **Why Option A is Correct** **Cicatricial Pemphigoid (Benign Mucous Membrane Pemphigoid)** is the most common cause of desquamative gingivitis. It is an autoimmune subepidermal blistering disease where antibodies target the basement membrane zone (specifically BP180/Laminin 332). Unlike Pemphigus, it primarily affects mucous membranes (oral, ocular, genital) and often leads to scarring (cicatrix). The "peeling" of the gingiva upon gentle brushing is a hallmark sign. ### **Why Other Options are Incorrect** * **B. Chronic Discoid Lupus Erythematosus (CDLE):** While it can cause oral ulcers, they typically present as central erythema with peripheral radiating white striae (honeycomb pattern), usually on the buccal mucosa, not generalized desquamative gingivitis. * **C. Pemphigus:** Pemphigus vulgaris frequently involves the mouth, but it presents as fragile, ragged, non-healing ulcers and erosions on the soft palate and buccal mucosa. While it can cause desquamative gingivitis, it is statistically less common than Pemphigoid for this specific presentation and usually involves other skin sites with a positive Nikolsky sign. * **D. Psoriasis:** Oral psoriasis is extremely rare. It typically presents as "geographic tongue" (erythema migrans) rather than desquamative gingivitis. ### **NEET-PG High-Yield Pearls** * **Desquamative Gingivitis:** Not a diagnosis but a clinical sign. Top 3 causes: 1. Cicatricial Pemphigoid, 2. Lichen Planus, 3. Pemphigus Vulgaris. * **Ocular Involvement:** In Mucous Membrane Pemphigoid, always check the eyes for **symblepharon** (adhesion of eyelid to eyeball), as it can lead to blindness. * **Histopathology:** Pemphigoid shows **subepidermal** blisters with linear IgG/C3 at the BMZ on Direct Immunofluorescence (DIF).

Q: Which of the following is true about erythema multiforme?

Target lesions are seen. **Erythema Multiforme (EM)** is an acute, self-limiting, immune-mediated hypersensitivity reaction. It is characterized by the sudden onset of symmetric cutaneous lesions. ### **Explanation of Options:** * **Option B (Correct):** The hallmark of EM is the **target (iris) lesion**. A classic target lesion consists of three concentric zones: a central dusky/blistering area, a surrounding pale edematous ring, and a peripheral erythematous halo. These are typically found on the extremities (acral distribution). * **Option A (Incorrect):** The most common trigger for EM is **Herpes Simplex Virus (HSV)**, specifically HSV-1. While drugs (like NSAIDs or sulfonamides) can cause it, viral infections account for the majority of cases. HIV is not a primary trigger. * **Option C (Incorrect):** Unlike Stevens-Johnson Syndrome (SJS), EM usually presents with **minimal or no prodromal symptoms**. If present, they are mild (low-grade fever or malaise). * **Option D (Incorrect):** Mucosal involvement occurs in **EM Major**, but it is generally less frequent and less severe than in SJS/TEN. In **EM Minor**, mucosal involvement is typically absent. ### **High-Yield Clinical Pearls for NEET-PG:** 1. **Classification:** * **EM Minor:** No mucosal involvement, minimal systemic symptoms. * **EM Major:** Involvement of at least one mucosa (usually oral). 2. **Pathogenesis:** It is a **Type IV (Cell-mediated) hypersensitivity** reaction. 3. **Histology:** Shows "satellite cell necrosis" (individual keratinocyte death) and subepidermal edema. 4. **Key Differentiator:** EM is now considered a distinct entity from SJS/TEN. EM is usually post-infectious (HSV), whereas SJS/TEN is almost always drug-induced. 5. **Distribution:** Centripetal spread (starts at extremities and moves towards the trunk).

Q: Which of the following is mainly a non-inflammatory blistering disorder?

Epidermolysis bullosa. **Explanation:** The core distinction in blistering diseases lies between **inflammatory** (immunological) and **non-inflammatory** (mechanobullous) etiologies. **Why Epidermolysis Bullosa (EB) is correct:** Epidermolysis bullosa is a group of genetic, non-inflammatory disorders characterized by structural defects in the proteins that anchor the epidermis to the dermis (e.g., Keratin 5/14, Type VII collagen). Because the primary pathology is a **mechanical/structural weakness** rather than an immune-mediated attack, there is a lack of significant inflammatory infiltrate. Blisters typically occur in response to minor trauma or friction (mechanobullous). **Why the other options are incorrect:** * **Pemphigus (B) and Bullous Pemphigoid (D):** These are **autoimmune** blistering diseases. They involve an active inflammatory process where autoantibodies (IgG) target desmosomal or hemidesmosomal proteins, triggering an inflammatory cascade and recruitment of inflammatory cells. * **Dermatitis Herpetiformis (A):** This is a highly inflammatory condition associated with Celiac disease. It is characterized by IgA deposits at the dermal papillae, leading to the recruitment of **neutrophils** and the formation of microabscesses. **High-Yield Clinical Pearls for NEET-PG:** 1. **Nikolsky Sign:** Positive in Pemphigus Vulgaris (intraepidermal); Negative in Bullous Pemphigoid (subepidermal). 2. **EB Simplex:** Most common type; defect in Keratin 5 and 14. 3. **Dystrophic EB:** Defect in Type VII collagen (anchoring fibrils); leads to scarring and "mitten-hand" deformities. 4. **Direct Immunofluorescence (DIF):** Essential for diagnosing inflammatory blisters (Options A, B, D) but typically negative/non-diagnostic for EB.

Q: Recessive dystrophic epidermolysis bullosa occurs due to an alteration in which type of collagen?

Type 7 collagen. **Explanation:** **Recessive Dystrophic Epidermolysis Bullosa (RDEB)** is a severe mechanobullous disorder characterized by skin fragility and blistering. The correct answer is **Type 7 collagen** because it is the primary component of **anchoring fibrils**. These fibrils are responsible for tethering the basement membrane (lamina densa) to the underlying papillary dermis. In RDEB, mutations in the *COL7A1* gene lead to a deficiency or total absence of Type 7 collagen, causing the sub-epidermal layers to separate easily upon minor trauma. **Analysis of Incorrect Options:** * **Type 4 collagen:** This is a major structural component of the **lamina densa** itself. While vital for the basement membrane zone, it is not the primary defect in dystrophic EB. * **Type 6 collagen:** This type is found in the interstitial matrix and is associated with conditions like Bethlem myopathy or Ullrich congenital muscular dystrophy, not primary blistering skin diseases. * **Type 8 collagen:** This is primarily found in vascular endothelium and Descemet’s membrane in the cornea; it does not play a role in the pathogenesis of Epidermolysis Bullosa. **Clinical Pearls for NEET-PG:** * **Hallmark of Dystrophic EB:** Blistering occurs **below the lamina densa** (sub-lamina densa). * **Clinical Features:** Healing with extensive **scarring**, milia formation, and "mitten-hand" deformity (pseudosyndactyly). * **Complication:** Patients have a significantly high risk of developing aggressive **Squamous Cell Carcinoma (SCC)** in chronic scars. * **Memory Aid:** "Dystrophic = Deeper (Type 7) | Junctional = Junction (Laminin 332) | Simplex = Superficial (Keratin 5/14)."

Question 1

Defects in which of the following does NOT cause blistering?

Accepted Answer

Filaggrin

Answer

Collagen VII and pectin

Answer

Laminin

Answer

Keratin

Question 2

What is the drug of choice for dermatitis herpetiformis?

Accepted Answer

Dapsone

Answer

Rifampicin

Answer

Ketoconazole

Answer

Azithromycin

Question 3

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 4

Which condition is characterized by severe bullous erythema multiforme with oral, ocular, and genital lesions?

Accepted Answer

Stevens-Johnson syndrome

Answer

Darier's disease

Answer

Reiter syndrome

Answer

All of the above

Question 5

A 60-year-old patient presented with several bullous lesions for the last 3 days; each bulla was surrounded by an erythematous halo. There were multiple target lesions and oral erosions. What is the most likely diagnosis?

Accepted Answer

Stevens-Johnson syndrome

Answer

Chickenpox

Answer

Herpes simplex

Answer

Herpes zoster

Question 6

Intraepidermal bullae formation occurs in which of the following conditions?

Accepted Answer

Pemphigus vulgaris

Answer

Bullous Impetigo

Answer

Bullous pemphigoid

Answer

Dermatitis herpetiformis

Question 7

A twenty-one-year-old woman complains that regular, gentle brushing of her teeth is painful and causes profuse bleeding. Oral examination reveals the loss of epithelium from the attached gingiva of both arches. Which of the following dermatological problems is this patient most likely to have?

Accepted Answer

Benign mucous membrane pemphigoid

Answer

Chronic discoid lupus erythematosus

Answer

Pemphigus

Answer

Psoriasis

Question 8

Which of the following is true about erythema multiforme?

Accepted Answer

Target lesions are seen

Answer

Triggered mainly by HIV infection

Answer

Full blown prodromal symptoms

Answer

Involvement of mucosa more common

Question 9

Which of the following is mainly a non-inflammatory blistering disorder?

Accepted Answer

Epidermolysis bullosa

Answer

Dermatitis herpetiformis

Answer

Pemphigus

Answer

Bullous pemphigoid

Question 10

Recessive dystrophic epidermolysis bullosa occurs due to an alteration in which type of collagen?

Accepted Answer

Type 7 collagen

Answer

Type 4 collagen

Answer

Type 6 collagen

Answer

Type 8 collagen

Blistering Diseases — MCQs

Blistering Diseases — MCQs

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