Immunobullous Disorders — MCQs
Which of the following is NOT a characteristic of pemphigus vulgaris?
A skin biopsy shows acantholysis with intraepidermal blistering. Which immunofluorescence pattern would confirm pemphigus vulgaris?
A 40 year old male reported with recurrent episodes of oral ulcers, large areas of denuded skin and flaccid vesiculo-bullous eruptions. Which is the most important bedside investigation helpful in establishing the diagnosis -
Which of the following statements about mucous membrane pemphigoid is correct?
A patient presents with the skin lesions shown in the image. While evaluating for possible blistering disorders, all of the following conditions could present with similar morphology EXCEPT:
A child presents with grouped vesicles on an erythematous base on the buttocks. What is the most likely diagnosis?
A skin biopsy shows suprabasilar acantholysis with 'row of tombstones' appearance. Which immunofluorescence pattern would confirm pemphigus vulgaris?
The following image shows a flaccid bulla. This finding is characteristically seen in:
Which of the following is NOT associated with erythema nodosum?
Acantholysis is seen in all except which of the following conditions?
Immunobullous Disorders Indian Medical PG Practice Questions and MCQs
Question 1: Which of the following is NOT a characteristic of pemphigus vulgaris?
- A. Oral erosions
- B. Tzanck smear showing acantholytic cells
- C. Positive Nikolsky’s sign
- D. Subepidermal bulla (Correct Answer)
Explanation: ***Subepidermal bulla*** - Pemphigus vulgaris is characterized by **intraepidermal bullae** resulting from acantholysis (loss of cohesion between keratinocytes), not subepidermal bullae. - **Subepidermal bullae** are characteristic of conditions like **bullous pemphigoid**, where the split occurs below the epidermis. *Positive Nikolsky’s sign* - The **Nikolsky's sign** is positive in pemphigus vulgaris, indicating the fragility of the skin where gentle lateral pressure causes epidermal shearing. - This sign is a direct result of the **intraepidermal blistering** due to weakened cell-to-cell adhesion. *Oral erosions* - **Oral erosions** are a very common and often the initial manifestation of pemphigus vulgaris, frequently preceding skin lesions. - These painful erosions are persistent and heal slowly, sometimes making eating difficult. *Tzanck smear showing acantholytic cells* - A **Tzanck smear** from a fresh blister in pemphigus vulgaris typically reveals **acantholytic cells**, which are detached, rounded keratinocytes with basophilic cytoplasm. - The presence of acantholytic cells confirms the **loss of intercellular adhesion** within the epidermis, a hallmark of pemphigus.
Question 2: A skin biopsy shows acantholysis with intraepidermal blistering. Which immunofluorescence pattern would confirm pemphigus vulgaris?
- A. Fishnet pattern of IgG (Correct Answer)
- B. Linear IgA deposits
- C. Granular IgG deposits
- D. Linear C3 deposits
Explanation: ***Fishnet pattern of IgG*** - A **fishnet or reticular pattern** of **IgG deposition** on direct immunofluorescence (DIF) is characteristic of **pemphigus vulgaris**, indicating antibodies targeting **desmoglein 1 and 3** in the intracellular spaces of the epidermis. - This pattern corresponds to the **acantholysis** observed on biopsy, where loss of cell adhesion leads to intraepidermal blistering. *Linear IgA deposits* - **Linear IgA deposits** at the **dermal-epidermal junction** are characteristic of **linear IgA bullous dermatosis**, a blistering disorder distinct from pemphigus. - This pattern signifies **antibodies targeting components of the basement membrane zone**, not intraepidermal desmogleins. *Granular IgG deposits* - **Granular IgG deposits** in the skin are typically seen in conditions like **lupus erythematosus** or **dermatitis herpetiformis** when IgA is targeted, signifying immune complex deposition or specific antigen targeting. - This pattern is not associated with the pathogenesis of pemphigus vulgaris, which involves antibodies against desmosomal proteins. *Linear C3 deposits* - **Linear C3 deposits**, particularly at the **dermal-epidermal junction**, are a hallmark of **bullous pemphigoid**, often accompanied by linear IgG or IgA. - This indicates **complement activation** at the basement membrane zone, leading to subepidermal blistering, not the intraepidermal blistering seen in pemphigus vulgaris.
Question 3: A 40 year old male reported with recurrent episodes of oral ulcers, large areas of denuded skin and flaccid vesiculo-bullous eruptions. Which is the most important bedside investigation helpful in establishing the diagnosis -
- A. Tzanck smear from the floor of bulla (Correct Answer)
- B. Gram staining of blister fluid
- C. Culture and sensitivity of blister fluid
- D. Skin biopsy with immunofluorescence
Explanation: ***Tzanck smear from the floor of bulla*** - A Tzanck smear from the floor of a bulla will reveal **acantholytic cells** (rounded keratinocytes that have lost their intercellular connections), which are characteristic of pemphigus, consistent with recurrent oral ulcers, denuded skin, and flaccid vesiculobullous eruptions. - This **bedside test** provides a rapid diagnosis by demonstrating the cytological features of acantholysis, differentiating it from other blistering disorders. *Gram staining of blister fluid* - This test is primarily used to identify **bacterial infections** and would show the morphology and Gram-staining characteristics of any bacteria present. - It would not provide information about the **acantholysis** or autoimmune nature of the blistering condition described. *Culture and sensitivity of blister fluid* - This investigation identifies **specific bacterial pathogens** and their antibiotic susceptibilities, which is useful for treating bacterial infections. - It would not help in diagnosing **autoimmune blistering diseases** like pemphigus, where bacteria are not the primary cause of the lesions. *Skin biopsy with immunofluorescence* - While a **skin biopsy with direct immunofluorescence** is the gold standard for confirming pemphigus by detecting autoantibodies, it is an **invasive procedure** requiring laboratory processing and is not considered a rapid bedside investigation. - The question specifically asks for the "most important **bed-side investigation**" helpful in establishing the diagnosis rapidly.
Question 4: Which of the following statements about mucous membrane pemphigoid is correct?
- A. It presents as multiple, painful ulcers preceded by bullae which form below the epithelium at the basement membrane.
- B. Oral lesions may be found in any region, especially in the attached gingiva; ocular lesions can lead to blindness if untreated. (Correct Answer)
- C. None of the options.
- D. It primarily affects young adults and children, with peak incidence in the 2nd to 3rd decade of life.
Explanation: ***Oral lesions may be found in any region, especially in the attached gingiva; ocular lesions can lead to blindness if untreated.*** - **Mucous membrane pemphigoid (MMP)** frequently manifests in the **oral cavity**, with the attached gingiva being the most common site, often presenting as **desquamative gingivitis**. - **Ocular involvement** occurs in 60-70% of cases and is a critical feature that can cause conjunctival scarring, symblepharon formation, ankyloblepharon, and eventually **blindness** if not recognized and managed early. - This statement captures the two most clinically significant features of MMP: the characteristic oral presentation and the sight-threatening ocular complications. *It presents as multiple, painful ulcers preceded by bullae which form below the epithelium at the basement membrane.* - While MMP does involve **subepithelial blister formation** at the basement membrane zone (confirmed by immunofluorescence showing linear IgG and C3 deposition), the clinical presentation is typically **chronic erosions and desquamation** rather than acute multiple painful ulcers. - The bullae in MMP are often **tense and intact initially** but rupture easily, leaving **slow-healing erosions** rather than the acute ulcerative picture this option suggests. - This description might be more characteristic of **pemphigus vulgaris** (which has flaccid, painful oral ulcers from intraepithelial bullae). *It primarily affects young adults and children, with peak incidence in the 2nd to 3rd decade of life.* - This is **incorrect**. MMP predominantly affects **middle-aged to elderly adults**, with peak incidence in the **6th to 7th decade of life** (ages 50-70 years). - The disease is rare in children and young adults, making this statement factually inaccurate.
Question 5: A patient presents with the skin lesions shown in the image. While evaluating for possible blistering disorders, all of the following conditions could present with similar morphology EXCEPT:
- A. Pemphigus vulgaris
- B. Pemphigus erythematosus
- C. Bullous pemphigoid (Correct Answer)
- D. Pemphigus vegetans
Explanation: ***Bullous pemphigoid*** - Presents with **tense bullae** on an erythematous base, typically in elderly patients, unlike the **umbilicated papules** seen in this image. - Involves **subepidermal blistering** with **linear IgG deposition** at the basement membrane zone, not the viral inclusions of Molluscum contagiosum. *Pemphigus vegetans* - A rare variant of pemphigus vulgaris characterized by **vegetating plaques and pustules** in intertriginous areas, not discrete umbilicated lesions. - Shows **intraepidermal acantholysis** with **suprabasal clefting**, histologically distinct from the viral cytopathic changes in Molluscum contagiosum. *Pemphigus vulgaris* - Presents with **flaccid bullae** and painful **mucosal erosions** due to **autoantibodies against desmoglein 1 and 3**. - The **Nikolsky sign** is positive, and lesions are erosive rather than the solid, pearl-like papules characteristic of Molluscum contagiosum. *Pemphigus erythematosus* - Features **erythematous, scaly, crusted lesions** primarily on the **face and upper trunk** with a butterfly distribution. - Combines features of **lupus erythematosus** and pemphigus foliaceus, showing superficial blistering unlike the viral papules in this case.
Question 6: A child presents with grouped vesicles on an erythematous base on the buttocks. What is the most likely diagnosis?
- A. Bullous impetigo
- B. Dermatitis herpetiformis
- C. Pemphigus
- D. Herpes simplex (Correct Answer)
Explanation: ***Herpes simplex*** - Herpes simplex virus (HSV) classically presents with **grouped vesicles on an erythematous base**, which perfectly matches this clinical presentation. - In **children**, HSV commonly affects the **buttocks** through autoinoculation or direct contact, especially in the diaper area. - The lesions are typically **painful and pruritic**, and may be preceded by tingling or burning sensation. - Diagnosis is confirmed by **Tzanck smear** (multinucleated giant cells), **PCR**, or **viral culture**. - Treatment includes **acyclovir** or other antivirals, especially for severe or recurrent cases. *Dermatitis herpetiformis* - While DH does present with intensely pruritic, grouped vesicles on an erythematous base, it is **extremely rare in children** and typically presents in **adults (3rd-4th decade)**. - Classic sites include **extensor surfaces** (elbows, knees), scalp, and buttocks, but the pediatric presentation makes this diagnosis unlikely. - It is strongly associated with **celiac disease** and responds to **gluten-free diet** and **dapsone**. *Bullous impetigo* - Bullous impetigo presents with **flaccid bullae** that rupture to form **honey-colored crusts**, not grouped vesicles. - It is a **bacterial infection** caused by *Staphylococcus aureus* producing exfoliative toxin. - Common in **young children**, particularly in warm, humid conditions. *Pemphigus* - Pemphigus is **extremely rare in children** and causes **fragile bullae** that easily rupture, leading to erosions. - Typically affects **mucous membranes first** (oral cavity), then skin. - It is an **autoimmune blistering disease** with antibodies against desmoglein, causing intraepidermal acantholysis.
Question 7: A skin biopsy shows suprabasilar acantholysis with 'row of tombstones' appearance. Which immunofluorescence pattern would confirm pemphigus vulgaris?
- A. Linear IgA deposits
- B. Fishnet pattern of IgG (Correct Answer)
- C. Granular IgG deposits
- D. Linear C3 deposits
Explanation: ***Fishnet pattern of IgG*** - Pemphigus vulgaris is characterized by **autoantibodies** (predominantly **IgG**) directed against **desmogleins 1 and 3**, components of desmosomes in the epidermis. - This binding leads to the **loss of cell adhesion** (acantholysis) and results in the characteristic **net-like or "fishnet" pattern** of IgG positivity on direct immunofluorescence (DIF), outlining keratinocyte cell surfaces. *Linear IgA deposits* - **Linear IgA bullous dermatosis** is characterized by the presence of continuous linear deposits of IgA along the **dermoepidermal junction** on direct immunofluorescence. - This condition is clinically and immunologically distinct from pemphigus vulgaris, which involves **intraepidermal deposition of IgG**. *Granular IgG deposits* - **Granular IgG deposits** at the dermoepidermal junction are typically seen in conditions like **lupus erythematosus**, particularly in the form of a **lupus band test**, rather than in blistering diseases like pemphigus. - Pemphigus involves **intercellular IgG deposition** within the epidermis, not granular deposits at the junction. *Linear C3 deposits* - **Linear C3 deposits** (often accompanied by IgG) along the **dermoepidermal junction** are characteristic of **bullous pemphigoid**, another autoimmune blistering disease. - Unlike pemphigus vulgaris, bullous pemphigoid involves autoantibodies targeting hemidesmosomes, leading to subepidermal blistering rather than intraepidermal acantholysis.
Question 8: The following image shows a flaccid bulla. This finding is characteristically seen in:
- A. Pemphigus vegetans
- B. Pemphigus vulgaris (Correct Answer)
- C. Pemphigus erythematosus
- D. Bullous pemphigoid
Explanation: ***Pemphigus vulgaris*** - The image shows a **flaccid bulla** with purulent fluid, characteristic of **pemphigus vulgaris**. This condition is marked by autoantibodies against desmogleins 1 and 3, which are crucial for keratinocyte adhesion, leading to **intraepidermal blistering** and the **Nikolsky sign**. - The flaccid nature of the bulla, often leading to easy rupture and erosions, is a hallmark of superficial blistering in pemphigus vulgaris, caused by the **loss of cell-to-cell adhesion** within the epidermis. *Pemphigus vegetans* - This is a rare variant of pemphigus vulgaris characterized by **vegetating plaques** and **hyperkeratotic lesions**, particularly in intertriginous areas. - While it starts with bullae, the predominant feature is the development of fungating, vegetative lesions rather than the flaccid bulla seen here. *Pemphigus erythematosus* - Pemphigus erythematosus, also known as Senear-Usher syndrome, is considered a localized form of pemphigus foliaceus with features of **lupus erythematosus**. - It presents with **scaling, crusting, and erythematous lesions** resembling lupus, along with superficial bullae, typically on the face and scalp. *Bullous pemphigoid* - Bullous pemphigoid typically presents with **tense bullae** that are less prone to rupture, unlike the flaccid bulla shown in the image. - It is caused by autoantibodies against hemidesmosomal proteins (BP180 and BP230), resulting in **subepidermal blistering**, meaning the blister forms below the epidermis and is therefore more resilient.
Question 9: Which of the following is NOT associated with erythema nodosum?
- A. Pemphigus vulgaris (Correct Answer)
- B. Tuberculosis
- C. Sarcoidosis
- D. Leprosy
Explanation: ***Pemphigus vulgaris*** - **Pemphigus vulgaris** is an **autoimmune blistering disease** that affects the skin and mucous membranes, characterized by flaccid bullae, not subcutaneous nodules. - Its pathophysiology involves **autoantibodies** against **desmoglein 1 and 3**, leading to **acantholysis**, which is distinct from the inflammatory changes seen in erythema nodosum. *Tuberculosis* - **Tuberculosis (TB)** is a common infectious cause of **erythema nodosum**, especially in regions with high TB prevalence. - The development of erythema nodosum in TB is often considered a **hypersensitivity reaction** to mycobacterial antigens. *Sarcoidosis* - **Sarcoidosis** is a systemic granulomatous disease, and **erythema nodosum** can be a prominent cutaneous manifestation, particularly in **Löfgren's syndrome**. - Its presence with **bilateral hilar lymphadenopathy** and **arthralgia** is highly suggestive of acute sarcoidosis. *Leprosy* - **Leprosy**, caused by *Mycobacterium leprae*, can be associated with **erythema nodosum leprosum (ENL)**, which is a type 2 lepra reaction. - **ENL** involves the formation of painful, tender, inflamed nodules that resemble erythema nodosum and is linked to elevated immune complex deposition.
Question 10: Acantholysis is seen in all except which of the following conditions?
- A. Pemphigus vulgaris
- B. Darier's disease
- C. Bullous pemphigoid (Correct Answer)
- D. SSSS
Explanation: ***Bullous pemphigoid*** - This condition involves **subepidermal blistering**, meaning the separation of the epidermis from the dermis, which occurs *below* the **basal cell layer**. - **Acantholysis**, the loss of cohesion between keratinocytes *within* the epidermis, does not occur in bullous pemphigoid, making it the correct answer. *Pemphigus vulgaris* - This is an **autoimmune blistering disease** characterized by the presence of autoantibodies against **desmoglein 3** (and often desmoglein 1). - This leads to intraepidermal blistering caused by **acantholysis**, the primary pathophysiological event. *Darier's disease* - This is an **autosomal dominant genodermatosis** characterized by abnormal keratinization and acantholysis. - Due to defects in **ATP2A2** (encoding SERCA2), there is impaired calcium handling in keratinocytes, leading to premature desmosomal degradation and **acantholysis**. *SSSS (Staphylococcal Scalded Skin Syndrome)* - Caused by **exfoliative toxins** (ETA and ETB) produced by *Staphylococcus aureus* that target **desmoglein 1**. - The cleavage of desmoglein 1 results in superficial **intraepidermal blistering** due to **acantholysis** in the granular layer of the epidermis.
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