Linear IgA Bullous Dermatosis Indian Medical PG Practice Questions and MCQs
Practice Indian Medical PG questions for Linear IgA Bullous Dermatosis. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Linear IgA Bullous Dermatosis Indian Medical PG Question 1: A 60-year-old female presents with eczematous itching lesions. Biopsy revealed a subepidermal cleft with Direct Immunofluorescence showing Linear C3 & IgG deposition along the basement membrane zone. What is the likely diagnosis?
- A. Pemphigus foliaceus
- B. Pemphigus Vulgaris
- C. Dermatitis herpetiformis
- D. Bullous Pemphigoid (Correct Answer)
Linear IgA Bullous Dermatosis Explanation: ***Bullous Pemphigoid***
- The presence of **eczematous itching lesions**, a **subepidermal cleft**, and **linear C3 and IgG deposition along the basement membrane zone** on direct immunofluorescence (DIF) are classic diagnostic features of Bullous Pemphigoid.
- This autoimmune blistering disease typically affects older individuals and is characterized by antibodies targeting components of the **hemidesmosomes**, specifically BP180 and BP230.
*Pemphigus foliaceus*
- This condition involves **intraepidermal blistering**, specifically within the granular layer, rather than a subepidermal cleft.
- DIF in Pemphigus foliaceus shows **intercellular IgG deposition** in the epidermis, not linear deposition along the basement membrane zone.
*Pemphigus Vulgaris*
- Pemphigus Vulgaris is characterized by **intraepidermal blistering** above the basal cell layer (**suprabasal clefting**), leading to fragile bullae that rupture easily.
- DIF typically reveals **intercellular IgG and C3 deposition** in a "chicken wire" pattern throughout the epidermis, which differs from the linear pattern seen in this case.
*Dermatitis herpetiformis*
- While Dermatitis herpetiformis is also an autoimmune blistering disease with itching lesions, its characteristic DIF finding is **granular IgA deposition** in the dermal papillae, not linear C3 and IgG at the basement membrane zone.
- Histopathology in Dermatitis herpetiformis shows **subepidermal vesicles** with neutrophil infiltration in the dermal papillae, but the direct immunofluorescence pattern is distinct.
Linear IgA Bullous Dermatosis Indian Medical PG 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
Linear IgA Bullous Dermatosis 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.
Linear IgA Bullous Dermatosis Indian Medical PG Question 3: A 58-year-old woman had a mitral valve replacement, and was placed on anticoagulants and prophylactic antibiotics following her surgery. Five days after her surgery, she developed a sharply demarcated, erythematous rash on her left thigh. Two days after the rash appeared, large hemorrhagic bullae began to form in the area of the rash. Which of the following medications most likely caused the patient's rash?
- A. Cefazolin
- B. Aspirin
- C. Heparin
- D. Warfarin (Correct Answer)
Linear IgA Bullous Dermatosis Explanation: ***Warfarin***
- The rash described, with sharply demarcated erythema, followed by hemorrhagic bullae, is highly suggestive of **warfarin-induced skin necrosis**. This rare but severe complication typically occurs in the first few days of therapy.
- Warfarin blocks vitamin K-dependent clotting factors (II, VII, IX, X) and also protein C and S. Initial decrease in protein C, which has a shorter half-life, leads to a transient hypercoagulable state and microvascular thrombosis, causing skin necrosis in susceptible individuals.
*Cefazolin*
- **Cefazolin** is a cephalosporin antibiotic. While antibiotics can cause various skin reactions, including generalized rashes or Stevens-Johnson syndrome, it is not typically associated with localized, sharply demarcated hemorrhagic bullae as seen in this case.
- **Allergic reactions** to cefazolin usually manifest as urticaria, maculopapular rash, or anaphylaxis, lacking the specific progression to hemorrhagic necrosis.
*Aspirin*
- **Aspirin** is an antiplatelet agent. Adverse skin reactions to aspirin are uncommon but can include urticaria, angioedema, or aspirin-exacerbated respiratory disease.
- It does not characteristically cause **hemorrhagic bullae** or skin necrosis. Its mechanism of action primarily inhibits platelet aggregation, not coagulation factors that would lead to such necrotizing lesions.
*Heparin*
- **Heparin-induced thrombocytopenia (HIT)** is a well-known complication of heparin, which can lead to thrombotic events, but typically presents with new thrombosis and a drop in platelet count, not localized hemorrhagic bullae or skin necrosis as the primary dermatological manifestation.
- **Heparin-induced skin lesions** usually occur at injection sites and often appear as erythematous, pruritic plaques or necrotic lesions only in the context of HIT with associated thrombosis, which differs from the presentation given.
Linear IgA Bullous Dermatosis Indian Medical PG Question 4: A 40-year-old male developed persistent oral ulcers, followed by multiple flaccid bullae on the trunk and extremities. Direct immunofluorescence examination of a skin biopsy showed intercellular IgG deposits in the epidermis. What is the most probable diagnosis?
- A. Pemphigus vulgaris (Correct Answer)
- B. Bullous Pemphigoid
- C. Bullous Lupus erythematosus
- D. Epidermolysis bullosa acquisita
Linear IgA Bullous Dermatosis Explanation: ***Pemphigus vulgaris***
- The presence of **persistent oral ulcers** followed by **flaccid bullae** on the trunk and extremities are classic clinical features.
- **Direct immunofluorescence (DIF)** showing **intercellular IgG deposits** in the epidermis confirms the diagnosis, indicating antibodies against **desmogleins** within the desmosomes.
*Bullous Pemphigoid*
- Characterized by **tense bullae**, unlike the flaccid bullae seen in this case, and typically affects older individuals.
- DIF would show **linear IgG and C3 deposits along the dermal-epidermal junction**, not intercellular epidermal deposits.
*Bullous Lupus erythematosus*
- This condition is rare and presents with **tense bullae** and other systemic manifestations of lupus erythematosus.
- DIF usually shows granular or linear deposits of **IgG, IgA, or C3 at the dermal-epidermal junction**, sometimes in a "lupus band" pattern, but not intercellular epidermal IgG.
*Epidermolysis bullosa acquisita*
- Presents with skin fragility and **blisters in response to trauma**, particularly on acral surfaces, with features resembling **dystrophic epidermolysis bullosa**.
- DIF reveals **linear IgG or IgA deposits along the dermal-epidermal junction** targeting type VII collagen, distinguishing it from pemphigus vulgaris.
Linear IgA Bullous Dermatosis Indian Medical PG Question 5: A child presented with itchy plaques over the neck, the bilateral popliteal and cubital fossa. What could be the diagnosis?
- A. Dermatitis herpetiformis
- B. Psoriasis
- C. Pemphigus vegetans
- D. Atopic dermatitis (Correct Answer)
Linear IgA Bullous Dermatosis Explanation: **Atopic dermatitis**
- The presentation of **itchy plaques** in the anatomical locations described (neck, bilateral popliteal fossa, and cubital fossa) is highly characteristic of **atopic dermatitis** in children.
- Atopic dermatitis typically involves **flexural surfaces** in older children and adults, and is characterized by **intense pruritus**.
*Dermatitis herpetiformis*
- This condition presents with **extremely itchy, grouped vesicles and papules**, primarily on extensor surfaces, buttocks, and scalp.
- It is strongly associated with **celiac disease** and is unlikely to present as plaques in flexural areas.
*Psoriasis*
- Psoriasis typically presents with **well-demarcated, erythematous plaques** covered with **silvery scales**, often on extensor surfaces (knees, elbows) and the scalp.
- While it can occur in flexural areas (inverse psoriasis), **itching is usually less prominent** than in atopic dermatitis, and the characteristic scaling is usually present.
*Pemphigus vegetans*
- Pemphigus vegetans is a rare variant of pemphigus, characterized by **verrucous, vegetative lesions** and **bullae**, often in intertriginous areas.
- This condition is a chronic autoimmune blistering disease and does not typically present as simple itchy plaques in a child.
Linear IgA Bullous Dermatosis Indian Medical PG Question 6: A patient presents with skin lesions and erosions on the buccal mucosa. The immunofluorescence image is shown. What is the most likely diagnosis?
- A. Bullous pemphigoid
- B. Pemphigus vulgaris (Correct Answer)
- C. Linear IgA disease
- D. Dermatitis herpetiformis
Linear IgA Bullous Dermatosis Explanation: ***Pemphigus vulgaris***
- The combination of **flaccid blisters/erosions** on the skin and **buccal mucosal lesions** is characteristic of pemphigus vulgaris. The image showing **intercellular IgG deposits** (a "chicken wire" pattern) in the epidermis confirms the diagnosis on immunofluorescence.
- Pemphigus vulgaris is an **autoimmune blistering disease** caused by autoantibodies against **desmoglein 1 and 3**, leading to acantholysis (loss of cell adhesion) within the epidermis.
*Bullous pemphigoid*
- This condition typically presents with **tense bullae** that are less prone to rupture, and **mucosal involvement is rare**.
- Immunofluorescence in bullous pemphigoid shows **linear IgG and C3 deposits at the dermoepidermal junction**, not an intercellular epidermal pattern.
*Linear IgA disease*
- Characterized by **linear IgA deposition along the basement membrane zone** on direct immunofluorescence.
- Clinically, it presents with **blisters** that can be variable in appearance, but the pathognomonic immunofluorescence pattern is distinct.
*Dermatitis herpetiformis*
- Presents with very **pruritic vesicles and papules**, primarily on extensor surfaces, and is strongly associated with **celiac disease**.
- Direct immunofluorescence reveals **granular IgA deposits in the dermal papillae**, which is distinct from the intercellular IgG pattern seen here.
Linear IgA Bullous Dermatosis Indian Medical PG Question 7: Identify the diagnosis based on the dermatology immunofluorescence (IF) image provided.
- A. Pemphigus vulgaris
- B. Pemphigus foliaceus
- C. Bullous pemphigoid
- D. Dermatitis herpetiformis (Correct Answer)
Linear IgA Bullous Dermatosis Explanation: ***Dermatitis herpetiformis***
- The immunofluorescence image shows **granular IgA deposits** at the **dermal papillae region**, which is characteristic of dermatitis herpetiformis.
- This condition is strongly associated with **celiac disease** and presents with intensely pruritic papules and vesicles.
*Pemphigus vulgaris*
- Immunofluorescence in pemphigus vulgaris typically shows a **fishnet pattern** of IgG deposits throughout the **epidermis**, reflecting antibodies against desmoglein 3 and 1.
- This pattern is an intercellular deposition, not granular at the dermal papillae.
*Pemphigus foliaceus*
- Similar to pemphigus vulgaris, pemphigus foliaceus also exhibits **intercellular IgG deposits** in the epidermis, but it is usually more superficial, targeting desmoglein 1.
- The image does not show this intercellular epidermal staining.
*Bullous pemphigoid*
- Bullous pemphigoid is characterized by **linear IgG and C3 deposits along the dermal-epidermal junction** (basement membrane zone).
- The image distinctly shows granular IgA, not linear IgG/C3, and specifically in the dermal papillae.
Linear IgA Bullous Dermatosis Indian Medical PG Question 8: The following lesion appears on the leg of a patient of ulcerative colitis. All are useful in management except:
- A. Steroids
- B. Sulfapyridine (Correct Answer)
- C. Procto-colectomy
- D. Infliximab
Linear IgA Bullous Dermatosis Explanation: ***Sulfapyridine***
- The image shows **pyoderma gangrenosum**, a painful ulcerative skin condition often associated with inflammatory bowel disease like ulcerative colitis. Among the given options, **sulfapyridine** has the **least established role** in pyoderma gangrenosum management.
- **Sulfapyridine** is an inactive component of **sulfasalazine** and primarily acts as an **antibacterial agent**. While sulfasalazine has been reported in some PG cases, sulfapyridine alone is not a recognized treatment for the inflammatory, non-infectious nature of pyoderma gangrenosum.
- Unlike the other options which have well-established roles, sulfapyridine lacks strong evidence for efficacy in PG.
*Steroids*
- **Corticosteroids** (oral or topical) are the **first-line treatment** for pyoderma gangrenosum due to their potent anti-inflammatory and immunosuppressive effects.
- They help to reduce the inflammation and promote healing of the painful ulcers.
*Procto-colectomy*
- In cases of severe, refractory pyoderma gangrenosum associated with ulcerative colitis, **colectomy** can be a **definitive treatment** as it removes the underlying inflammatory trigger.
- This surgical intervention is considered when medical therapies are unsuccessful or when the colonic disease itself necessitates surgery.
*Infliximab*
- **Infliximab**, a **TNF-alpha inhibitor**, is a biologic agent effective in treating both ulcerative colitis and pyoderma gangrenosum.
- It is used in cases that are refractory to steroids or when patients cannot tolerate steroid therapy.
Linear IgA Bullous Dermatosis Indian Medical PG Question 9: A Tzanck smear from a patient with bullous lesions shows which of the following findings?
- A. Langerhans cells are seen
- B. Acantholysis (Correct Answer)
- C. Leucocytosis
- D. Absence of melanin pigment
Linear IgA Bullous Dermatosis Explanation: **Explanation:**
The **Tzanck smear** is a rapid bedside diagnostic test used in dermatology to examine cells from the base of a blister. The hallmark finding in autoimmune bullous diseases like **Pemphigus Vulgaris** is **Acantholysis**.
**Why Acantholysis is correct:**
Acantholysis refers to the loss of intercellular connections (desmosomes) between keratinocytes. In Pemphigus, autoantibodies attack desmogleins, causing the epidermal cells to detach from one another and become rounded. On a Tzanck smear, these are seen as **Tzanck cells**: large, round, nucleated keratinocytes with a peripheral rim of condensed cytoplasm (mourning-edged appearance).
**Why other options are incorrect:**
* **Langerhans cells:** These are antigen-presenting cells found in the stratum spinosum. While present in the skin, they are not the diagnostic feature of a Tzanck smear for bullous lesions.
* **Leucocytosis:** This refers to an elevated white blood cell count in the blood, which is a systemic finding and cannot be determined via a localized skin smear.
* **Absence of melanin pigment:** This is characteristic of vitiligo or albinism, not primary blistering disorders.
**NEET-PG High-Yield Pearls:**
1. **Tzanck Smear Indications:** Used primarily for **Herpes Simplex/Varicella** (shows multinucleated giant cells) and **Pemphigus Vulgaris** (shows acantholytic cells).
2. **Stains used:** Giemsa, Wright’s, or Leishman stain.
3. **Bullous Pemphigoid:** Unlike Pemphigus, the Tzanck smear in Bullous Pemphigoid typically shows numerous **eosinophils** but *no* acantholysis, as the split is subepidermal.
4. **Hailey-Hailey Disease:** Also shows significant acantholysis on Tzanck smear (often described as a "dilapidated brick wall" on histology).
Linear IgA Bullous Dermatosis Indian Medical PG Question 10: Pemphigus vulgaris is caused by what type of process?
- A. Bacterial infection
- B. Viral infection
- C. Autoimmune process (Correct Answer)
- D. Fungal infection
Linear IgA Bullous Dermatosis Explanation: **Explanation:**
**Pemphigus vulgaris (PV)** is a chronic, life-threatening, intraepidermal blistering disease. The correct answer is **Autoimmune process** because PV is characterized by the production of IgG autoantibodies against **Desmogleins (Dsg1 and Dsg3)**. These are cadherin-type glycoproteins that form the "glue" of desmosomes, which hold epidermal keratinocytes together. When these antibodies bind, they cause a loss of cell-to-cell adhesion, a process known as **acantholysis**, leading to the formation of flaccid blisters.
**Why other options are incorrect:**
* **Bacterial, Viral, and Fungal infections:** While secondary infections (especially *Staphylococcus aureus*) are common complications due to denuded skin, the primary etiology of PV is not infectious. Blistering diseases caused by infections include Impetigo (bacterial) or Herpes Simplex (viral), which have distinct clinical and histological features.
**High-Yield NEET-PG Clinical Pearls:**
* **Target Antigens:** Dsg3 (primarily mucosal lesions) and Dsg1 (skin involvement).
* **Clinical Presentation:** Flaccid bullae that rupture easily, leaving painful erosions. Oral mucosa is often the first site involved.
* **Key Signs:** **Nikolsky sign** is positive (perilesional skin shears off with lateral pressure) and **Asboe-Hansen sign** is positive (bulla spreads laterally when pressed).
* **Histopathology:** Shows a "row of tombstones" appearance (basal layer remains attached to the basement membrane) and acantholytic cells (Tzanck cells).
* **Immunofluorescence:** Direct Immunofluorescence (DIF) shows a characteristic **"fishnet" or "lace-like" pattern** of IgG and C3 deposits.
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