Blistering Diseases Practice Questions

Q: Which of the following presents with a "string of pearls appearance"?

Linear IgA disease. **Explanation:** **Linear IgA Bullous Dermatosis (LABD)** is an autoimmune subepidermal blistering disease characterized by the linear deposition of IgA antibodies along the basement membrane zone. The "string of pearls" (or "cluster of jewels") appearance is a classic clinical descriptor for this condition, referring to the characteristic arrangement of new vesicles and bullae at the periphery of old, healing lesions. **Why the correct answer is right:** * **Linear IgA Disease:** The "string of pearls" appearance occurs because new blisters form in a ring-like (annular or polycyclic) pattern around a central crust or resolving lesion. This is a high-yield clinical sign often tested in NEET-PG. **Why the other options are incorrect:** * **Pemphigus Vulgaris:** Characterized by flaccid bullae and a positive **Nikolsky sign**. Histopathology shows "row of tombstones" appearance due to suprabasal acantholysis. * **Bullous Pemphigoid:** Presents with large, tense bullae in elderly patients. Direct Immunofluorescence (DIF) shows linear **IgG** and C3, not IgA. * **Dermatitis Herpetiformis:** Associated with Celiac disease. It presents with intensely pruritic, grouped (herpetiform) vesicles on extensor surfaces. DIF shows **granular IgA** deposits in dermal papillae. **Clinical Pearls for NEET-PG:** * **Drug-induced LABD:** Most commonly caused by **Vancomycin**. * **Target Antigen:** BP180 (collagen XVII) or LAD-1. * **Treatment of Choice:** **Dapsone** is the first-line treatment for Linear IgA disease. * **DIF Finding:** Continuous linear band of IgA along the dermo-epidermal junction.

Q: What is the commonest site of Herpes Gestationis?

Periumbilical region. **Explanation:** **Herpes Gestationis** (also known as **Pemphigoid Gestationis**) is a rare, autoimmune bullous dermatosis of pregnancy. Despite its name, it is not related to the herpes virus but is immunologically similar to Bullous Pemphigoid, involving IgG antibodies against the BP180 (BPAG2) protein. **1. Why the Periumbilical Region is Correct:** The characteristic initial presentation of Herpes Gestationis is the sudden onset of extremely pruritic, urticarial plaques and vesicles. In **50-90% of cases**, the eruption begins specifically in the **periumbilical region**. This is a classic diagnostic hallmark that distinguishes it from other pregnancy dermatoses like PUPPP (Pruritic Urticarial Papules and Plaques of Pregnancy), which typically spares the periumbilical area. **2. Analysis of Incorrect Options:** * **B. Flanks of abdomen:** While the rash can spread to the flanks, trunk, and extremities as the disease progresses, it is rarely the site of origin. * **C. Vulva:** Mucosal involvement (including the vulva or oral cavity) is rare in Herpes Gestationis, occurring in less than 20% of cases. * **D. Infraorbital:** The face and scalp are almost always spared in this condition. **3. Clinical Pearls for NEET-PG:** * **Timing:** Most commonly occurs during the **2nd or 3rd trimester** or immediate postpartum period. * **Immunofluorescence (High Yield):** Direct Immunofluorescence (DIF) shows **linear C3 deposition** along the basement membrane zone (BMZ). * **Fetal Risk:** Associated with an increased risk of premature delivery and transient neonatal skin lesions (due to passive transfer of antibodies). * **Recurrence:** Often recurs in subsequent pregnancies, often earlier and with increased severity ("flares" may also occur during menstruation or with OCP use).

Q: Granular deposition of IgA at dermal papillae on immunofluorescence is seen in which condition?

Dermatitis herpetiformis. **Explanation:** **Dermatitis Herpetiformis (DH)** is the correct answer. It is a chronic, intensely pruritic autoimmune blistering disease strongly associated with **Celiac disease** (gluten-sensitive enteropathy). The hallmark of DH is the presence of IgA antibodies against **epidermal transglutaminase (eTG)**. On Direct Immunofluorescence (DIF), these IgA complexes deposit in a characteristic **granular pattern** at the tips of the **dermal papillae**. **Analysis of Incorrect Options:** * **Herpes Gestationalis (Pemphigoid Gestationis):** This is a pregnancy-associated bullous disease. DIF shows a **linear deposition of C3** (and sometimes IgG) along the basement membrane zone (BMZ). * **Bullous Pemphigoid:** This is characterized by subepidermal blisters with a **linear deposition of IgG and C3** along the BMZ, targeting BP180 and BP230 antigens. * **IgA Dermatosis of Childhood (Linear IgA Bullous Dermatosis):** While this involves IgA, the deposition pattern is **linear** along the BMZ, not granular at the papillae. **High-Yield Clinical Pearls for NEET-PG:** * **Clinical Presentation:** Symmetric, extremely itchy vesicles/papules on extensor surfaces (elbows, knees, buttocks). * **Histopathology:** Shows **neutrophilic microabscesses** at the tips of dermal papillae. * **Association:** Nearly 90% of patients have asymptomatic gluten-sensitive enteropathy. * **Treatment of Choice:** **Dapsone** (provides rapid symptomatic relief) and a strict **Gluten-Free Diet** (long-term management).

Q: Toxic epidermal necrolysis (TEN) typically involves what percentage of body surface area?

Greater than 30%. **Explanation:** The classification of Stevens-Johnson Syndrome (SJS) and Toxic Epidermal Necrolysis (TEN) is based strictly on the percentage of **Body Surface Area (BSA)** affected by epidermal detachment. These conditions represent a spectrum of the same disease process, typically triggered by a hypersensitivity reaction to drugs (e.g., Sulfonamides, Antiepileptics, NSAIDs). * **SJS (Option A):** Involves **less than 10%** of the total BSA. It is the less severe end of the spectrum but still carries significant morbidity. * **SJS/TEN Overlap (Option B & C):** Involves **10% to 30%** of the BSA. This is a transitional zone where the disease is progressing beyond localized involvement. * **TEN (Option D):** Defined by epidermal detachment involving **greater than 30%** of the BSA. This is the most severe form, characterized by extensive "scalded" skin appearance and high mortality rates due to sepsis and fluid loss. **High-Yield Clinical Pearls for NEET-PG:** * **Pathology:** Characterized by widespread keratinocyte apoptosis mediated by **Fas-Fas ligand** interactions and **Granulysin**. * **Nikolsky Sign:** Positive (gentle pressure on the skin causes the epidermis to shear off). * **Mucosal Involvement:** Occurs in >90% of cases (oral, ocular, and genital). * **SCORTEN:** A prognostic scoring system used to predict mortality in SJS/TEN based on parameters like age, heart rate, malignancy, urea, and glucose. * **Management:** Immediate cessation of the offending drug and supportive care in a Burn Unit or ICU. Cyclosporine and IVIG are often considered as medical therapies.

Q: Coeliac disease is commonly associated with which bullous dermatosis?

Dermatitis herpetiformis. **Explanation:** **Dermatitis Herpetiformis (DH)** is the correct answer because it is considered the cutaneous manifestation of gluten-sensitive enteropathy (**Coeliac disease**). Both conditions share the same genetic predisposition (HLA-DQ2 and HLA-DQ8). In DH, IgA antibodies are formed against **epidermal transglutaminase (eTG)**, which cross-react with **tissue transglutaminase (tTG)** found in the gut. This leads to the characteristic subepidermal blisters and intense pruritus. **Analysis of Incorrect Options:** * **B. Erythema Multiforme:** This is a hypersensitivity reaction typically triggered by infections (most commonly Herpes Simplex Virus) or drugs. It is not linked to gluten sensitivity. * **C. Bullous Pemphigoid:** An autoimmune subepidermal blistering disease caused by IgG antibodies against BP180 and BP230. It is primarily seen in the elderly and has no association with Coeliac disease. * **D. Pemphigus Vulgaris:** An intraepidermal blistering disease caused by antibodies against Desmoglein 1 and 3. It involves the mucous membranes and skin but is not related to malabsorption syndromes. **High-Yield Clinical Pearls for NEET-PG:** * **Clinical Presentation:** Intensely pruritic, grouped (herpetiform) vesicles typically located on **extensor surfaces** (elbows, knees, buttocks). * **Histopathology:** Characterized by **neutrophilic microabscesses** at the tips of dermal papillae. * **Direct Immunofluorescence (DIF):** The gold standard for diagnosis, showing **granular IgA deposits** at the dermo-epidermal junction (tips of dermal papillae). * **Treatment:** The drug of choice is **Dapsone** (provides rapid symptomatic relief), but a **Gluten-Free Diet (GFD)** is essential for long-term management and resolving the underlying enteropathy.

Q: A patient presents with extremely pruritic excoriations and papules on their buttocks. Immunohistological examination of normal perilesional skin shows autoantibodies against epidermal transglutaminase and IgA deposition in the dermis. What is the diagnosis?

Dermatitis herpetiformis. **Explanation:** The clinical presentation and immunohistopathology are diagnostic of **Dermatitis Herpetiformis (DH)**. **Why the correct answer is right:** Dermatitis herpetiformis is a chronic, intensely pruritic autoimmune blistering disease strongly associated with **Celiac disease** (gluten-sensitive enteropathy). * **Clinical Presentation:** Characterized by symmetric, grouped (herpetiform) papulovesicles on extensor surfaces (buttocks, elbows, knees). Due to intense itching, patients often present with only **excoriations**. * **Immunopathology:** The hallmark is **granular IgA deposition** in the dermal papillae tips. The target autoantigen is **epidermal transglutaminase (eTG)**, which cross-reacts with tissue transglutaminase (tTG) found in the gut. **Why incorrect options are wrong:** * **Pemphigus vulgaris:** Characterized by flaccid bullae and oral mucosal involvement. Immunofluorescence shows **IgG** and C3 in a "fishnet" pattern against desmogleins, not IgA. * **Bullous Pemphigoid:** Presents with tense bullae in the elderly. Immunofluorescence shows **linear IgG** and C3 along the basement membrane zone (BMZ). * **Linear IgA disease:** While it involves IgA, the deposition is **linear** along the BMZ, not granular in the dermal papillae, and it is not typically associated with gluten sensitivity. **NEET-PG High-Yield Pearls:** * **Gold Standard Diagnosis:** Direct Immunofluorescence (DIF) of **perilesional** skin showing granular IgA. * **Associated HLA:** HLA-DQ2 and HLA-DQ8. * **Treatment of Choice:** **Dapsone** (provides rapid symptomatic relief) and a strict **Gluten-free diet** (long-term management). * **Histology:** Shows **neutrophilic microabscesses** at the tips of dermal papillae.

Q: A 2-day-old newborn girl, born out of a non-consanguinous marriage, was evaluated for tense blisters and areas of denuded skin that had been present since birth. The child develops these lesions while the mother handles her for bathing and feeding. The sibling of the child also has a history of developing similar lesions. What is the most likely diagnosis?

Congenital epidermolysis bullosa. ### Explanation **Correct Option: B. Congenital epidermolysis bullosa (EB)** The clinical presentation of **tense blisters** and **denuded skin** present since birth, triggered by minor mechanical trauma (handling for bathing/feeding), is the hallmark of **Epidermolysis Bullosa**. This is a group of genetic mechanobullous disorders characterized by skin fragility due to mutations in structural proteins (like keratins, laminin, or collagen). The positive family history (sibling affected) further supports a genetic etiology. **Why the other options are incorrect:** * **A. Congenital Syphilis:** Typically presents with a maculopapular rash, snuffles, or hemorrhagic bullae on palms and soles. It is not triggered by mechanical friction and usually lacks a sibling history of similar lesions. * **C. Langerhans Cell Histiocytosis (LCH):** In neonates, LCH usually presents as seborrheic dermatitis-like crusting, petechiae, or reddish-brown papules, rather than mechanobullous blistering. * **D. Congenital Bullous Ichthyosiform Erythroderma (Epidermolytic Ichthyosis):** While it presents with blisters at birth, it is characterized by generalized **erythroderma** (redness) and subsequent thick, verrucous scaling, which is absent in this case. **High-Yield Clinical Pearls for NEET-PG:** * **Nikolsky Sign:** Often positive in EB (especially EB Simplex). * **Classification:** 1. **EB Simplex:** Intraepidermal cleavage (Keratin 5/14 mutation). 2. **Junctional EB:** Cleavage at Lamina Lucida (Laminin 332 mutation). 3. **Dystrophic EB:** Sub-lamina densa cleavage (Type VII Collagen mutation); often leads to scarring and "mitten-hand" deformity. * **Management:** Primarily supportive; "non-adherent dressings" and avoiding trauma are key. * **Differential Diagnosis:** Always rule out Staphylococcal Scalded Skin Syndrome (SSSS) and Neonatal Pemphigus in blistering neonates.

Q: Which of the following conditions is characterized by the presence of typical lesions that manifest as target lesions?

Erythema Multiforme. **Explanation:** **Erythema Multiforme (EM)** is the classic condition associated with **target (iris) lesions**. These lesions typically consist of three concentric zones: a central dusky/blistering area, an intermediate pale edematous ring, and a peripheral erythematous halo. This hypersensitivity reaction is most commonly triggered by infections, particularly **Herpes Simplex Virus (HSV)** and *Mycoplasma pneumoniae*. **Why other options are incorrect:** * **Pemphigus (Vulgaris/Foliaceus):** Characterized by flaccid bullae and a positive Nikolsky sign due to acantholysis (loss of cell-to-cell adhesion). It does not present with targetoid morphology. * **Bullous Pemphigoid:** Presents as large, tense subepidermal bullae on an erythematous base, typically in the elderly. The primary pathology is at the dermo-epidermal junction (anti-BP180/230). * **Dermatitis Herpetiformis:** Characterized by intensely pruritic, grouped (herpetiform) vesicles on the extensors, strongly associated with Celiac disease and IgA deposits in dermal papillae. **High-Yield Clinical Pearls for NEET-PG:** * **EM Minor vs. Major:** EM Major involves at least two mucosal surfaces and is more severe, whereas EM Minor involves minimal to no mucosal involvement. * **Target Lesion Anatomy:** True target lesions have **three** distinct zones. "Atypical" target lesions (two zones) are more characteristic of Stevens-Johnson Syndrome (SJS). * **Histopathology:** EM shows interface dermatitis with necrotic keratinocytes. * **Most Common Trigger:** HSV-1 is the most frequent precipitant of recurrent EM.

Q: Sub-epidermal splitting is not found in which of the following conditions?

Pemphigus foliaceus. **Explanation:** The level of splitting in blistering diseases is determined by the specific target of the autoimmune or physical insult. Blisters are categorized as **intra-epidermal** (within the epidermis) or **sub-epidermal** (below the epidermis/at the dermo-epidermal junction). **Why Pemphigus Foliaceus is the correct answer:** Pemphigus foliaceus is an autoimmune disease where antibodies target **Desmoglein-1**. Since Desmoglein-1 is located in the upper layers of the epidermis, the split occurs high up in the **stratum granulosum**. This results in a very superficial, **intra-epidermal** blister. Because the roof is so thin, these blisters rupture easily, often presenting clinically as scales or crusts rather than intact bullae. **Analysis of incorrect options (Sub-epidermal splitting present):** * **Bullous Pemphigoid:** Antibodies target BP180 and BP230 in the hemidesmosomes. This causes the entire epidermis to detach from the dermis, resulting in a **sub-epidermal** split and tense bullae. * **Dermatitis Herpetiformis:** IgA deposits at the tips of dermal papillae lead to neutrophilic microabscesses and subsequent **sub-epidermal** separation. * **Burns:** Second-degree (partial-thickness) burns typically involve thermal damage that leads to fluid accumulation at the **dermo-epidermal junction**, causing sub-epidermal cleavage. **High-Yield Clinical Pearls for NEET-PG:** * **Pemphigus Vulgaris:** Split is **suprabasal** (intra-epidermal) due to Desmoglein-3 antibodies; shows "row of tombstones" appearance. * **Nikolsky Sign:** Positive in intra-epidermal conditions (Pemphigus) and negative in sub-epidermal conditions (Bullous Pemphigoid). * **Mnemonic:** "Foliaceus is Foliage" (Top of the tree/surface); "Vulgaris is Deep" (Bottom/suprabasal).

Question 1

Which of the following presents with a "string of pearls appearance"?

Accepted Answer

Linear IgA disease

Answer

Pemphigus vulgaris

Answer

Bullous pemphigoid

Answer

Dermatitis herpetiformis

Question 2

What is the commonest site of Herpes Gestationis?

Accepted Answer

Periumbilical region

Answer

Flanks of abdomen

Answer

Vulva

Answer

Infraorbital

Question 3

Granular deposition of IgA at dermal papillae on immunofluorescence is seen in which condition?

Accepted Answer

Dermatitis herpetiformis

Answer

Herpes gestationalis

Answer

Bullous pemphigoid

Answer

IgA dermatosis of childhood

Question 4

Itching associated with linear IgA deposition in dermal papillae is a feature of which of the following conditions?

Accepted Answer

Dermatitis herpetiformis

Answer

Bullous disease of childhood

Answer

Lichenoid bullous disease

Answer

Pemphigus vulgaris

Question 5

Toxic epidermal necrolysis (TEN) typically involves what percentage of body surface area?

Accepted Answer

Greater than 30%

Answer

Less than 10%

Answer

10-20%

Answer

20-30%

Question 6

Coeliac disease is commonly associated with which bullous dermatosis?

Accepted Answer

Dermatitis herpetiformis

Answer

Erythema multiforme

Answer

Bullous pemphigoid

Answer

Pemphigus vulgaris

Question 7

A patient presents with extremely pruritic excoriations and papules on their buttocks. Immunohistological examination of normal perilesional skin shows autoantibodies against epidermal transglutaminase and IgA deposition in the dermis. What is the diagnosis?

Accepted Answer

Dermatitis herpetiformis

Answer

Pemphigus vulgaris

Answer

Pemphigoid

Answer

Linear IgA disease

Question 8

A 2-day-old newborn girl, born out of a non-consanguinous marriage, was evaluated for tense blisters and areas of denuded skin that had been present since birth. The child develops these lesions while the mother handles her for bathing and feeding. The sibling of the child also has a history of developing similar lesions. What is the most likely diagnosis?

Accepted Answer

Congenital epidermolysis bullosa

Answer

Congenital syphilis

Answer

Langerhans cell histiocytosis

Answer

Congenital bullous ichthyosiform erythroderma

Question 9

Which of the following conditions is characterized by the presence of typical lesions that manifest as target lesions?

Accepted Answer

Erythema Multiforme

Answer

Pemphigus

Answer

Bullous pemphigoid

Answer

Dermatitis Herpetiformis

Question 10

Sub-epidermal splitting is not found in which of the following conditions?

Accepted Answer

Pemphigus foliaceus

Answer

Bullous pemphigoid

Answer

Dermatitis herpetiformis

Answer

Burns

Blistering Diseases — MCQs

Blistering Diseases — MCQs

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