Immunobullous Disorders (Pemphigus, Pemphigoid, DH) MCQs

Dermatology · 46 free questions with answers & explanations.

1. A 45-year-old woman presents with flaccid blisters in the oral cavity and over the trunk for 2 months. Nikolsky sign is positive. DIF shows IgG and C3 in a chicken-wire (intercellular) pattern throughout the epidermis. Anti-desmoglein 3 antibodies are positive. What is the diagnosis?
2. A 65-year-old diabetic man presents with tense blisters over the abdomen and thighs on an urticarial base. Nikolsky sign is negative. DIF shows linear IgG and C3 at the dermoepidermal junction. Anti-BP180 and anti-BP230 antibodies are elevated. What is the correct diagnosis?
3. A 30-year-old man presents with intensely pruritic, grouped vesicles over extensor surfaces of elbows, knees, and buttocks. He also has celiac disease. DIF of perilesional skin shows granular IgA deposits at the papillary dermis. What is the diagnosis?
4. A 50-year-old woman presents with superficial erosions over the face and chest. Biopsy shows subcorneal acantholysis with a grain-like pattern. DIF shows IgG in an intercellular pattern. Anti-desmoglein 1 antibodies are positive with negative anti-desmoglein 3. What is the diagnosis?
5. A 45-year-old woman presents with painful oral erosions and flaccid blisters on the trunk that rupture easily. DIF of perilesional skin shows intercellular IgG deposits in the epidermis. Electron microscopy would show dissolution of which structure?
6. In pemphigus vulgaris, the blister forms at which histological level?
7. A 60-year-old man has tense blisters over the flexures. DIF shows linear IgG and C3 at the dermoepidermal junction. The target antigen is located in which part of the basement membrane zone?
8. A 35-year-old woman on dapsone for dermatitis herpetiformis develops hemolytic anemia. Her G6PD level is normal. Which mechanism best explains her hemolysis?
9. Dermatitis herpetiformis is associated with IgA deposits in the papillary dermis. These deposits are directed against which antigen?
10. Which immunobullous disorder shows 'n-serrated' pattern on electron microscopy of the BMZ, distinguishing it from bullous pemphigoid which shows 'u-serrated' pattern?
11. A 55-year-old woman presents with tense blisters on an erythematous base, predominantly on the flexural areas and abdomen. Direct immunofluorescence (DIF) of perilesional skin shows linear IgG and C3 deposition at the dermoepidermal junction. The target antigen most likely has a molecular weight of:
12. In pemphigus vulgaris, the histopathological hallmark is acantholysis above the basal layer. Which of the following best describes the mechanism by which anti-desmoglein-3 antibodies cause acantholysis?
13. A 28-year-old man presents with intensely pruritic grouped vesicles on the elbows, knees, buttocks, and scalp. DIF of perilesional skin reveals granular IgA deposits at dermal papillary tips. Which associated condition should be screened for?
14. A 60-year-old man develops flaccid bullae on the trunk and oral erosions. Salt-split skin technique on patient's serum shows IgG binding exclusively to the ROOF (epidermal side). This pattern is most consistent with:
15. Which of the following pemphigus variants is characterized by IgG4 subclass predominance against desmoglein-1 only, with superficial subcorneal blistering and no mucosal involvement?
16. A 45-year-old woman on penicillamine for Wilson's disease develops oral erosions and flaccid blisters. Which drug-induced bullous disorder most closely resembles this presentation immunologically?
17. A 55-year-old woman presents with flaccid blisters over the trunk and oral erosions. Direct immunofluorescence shows intercellular IgG deposits in a 'fishnet' pattern throughout the epidermis. The target antigen responsible for this condition has a molecular weight of:
18. A patient with pemphigus foliaceus is being treated. The histopathological hallmark that distinguishes it from pemphigus vulgaris is acantholysis occurring at the level of:
19. In bullous pemphigoid, indirect immunofluorescence using salt-split skin shows IgG deposits on the:
20. A 35-year-old patient presents with intensely pruritic, grouped vesicles on the elbows and buttocks. DIF of perilesional skin shows granular IgA deposits at the dermal papillae. The most sensitive serological marker for the associated systemic disease is:
21. A pregnant woman at 30 weeks develops intensely pruritic urticarial papules and plaques, then tense blisters, starting around the umbilicus. DIF shows linear C3 with or without IgG at the BMZ. The target antigen is:
22. Linear IgA bullous dermatosis (LABD) in adults most commonly presents with:
23. In epidermolysis bullosa acquisita (EBA), the target antigen and immunofluorescence salt-split skin pattern respectively are:
24. A patient with refractory pemphigus vulgaris is considered for rituximab. The recommended dose used in pemphigus is based on which protocol, and what is the target cell?
25. A 55-year-old woman presents with flaccid blisters on normal-appearing skin. Biopsy shows intraepidermal acantholytic blister with 'tombstone' appearance of basal keratinocytes. Immunofluorescence shows IgG and C3 deposition in a 'chicken-wire' pattern. The target antigen is located in which layer?
26. A patient with pemphigus vulgaris refractory to prednisolone 1 mg/kg/day is considered for rituximab. Which of the following best describes the mechanism by which rituximab achieves remission in pemphigus?
27. A 70-year-old man presents with tense blisters on an urticarial base on the trunk and flexures. Histopathology shows subepidermal blistering with eosinophilic infiltrate. Salt-split skin immunofluorescence shows IgG deposits on the roof (epidermal side) of the split. The target antigen is most likely:
28. A child presents with intensely pruritic grouped papulovesicles on extensor surfaces of elbows, knees, and buttocks. Biopsy shows microabscesses at dermal papillary tips with neutrophils and fibrin. Direct immunofluorescence of perilesional skin shows granular IgA deposits at the dermoepidermal junction. The most appropriate treatment is:
29. In linear IgA bullous dermatosis (LABD) associated with vancomycin intake, the target antigen and the characteristic immunofluorescence pattern are respectively:
30. In pemphigus foliaceus, the histological split occurs at the level of the granular layer, unlike pemphigus vulgaris (suprabasal split). This is because the autoantibody in PF targets:
31. Mucous membrane pemphigoid (cicatricial pemphigoid) predominantly affects mucosae and causes scarring. Which antigen is targeted in the ocular-dominant (Brunsting-Perry) variant?
32. A 65-year-old man on oral furosemide develops multiple tense blisters on an erythematous base on the flexor surfaces. DIF of perilesional skin shows linear C3 and IgG at the DEJ. ELISA confirms antibodies against the NC16A domain of BP180. This is classic for:
33. Rituximab (anti-CD20) has become first-line therapy for moderate-to-severe pemphigus vulgaris. The primary mechanism by which rituximab induces remission in pemphigus is:
34. In epidermolysis bullosa acquisita (EBA), which antigen is targeted and where does it localise on salt-split skin on indirect immunofluorescence?
35. A 50-year-old woman presents with flaccid, easily ruptured blisters on normal-appearing skin and mucous membranes. Tzanck smear shows acantholytic cells. DIF shows intercellular IgG in a 'fish-net' pattern throughout the epidermis. The target antigen is:
36. Mucous membrane pemphigoid (cicatricial pemphigoid) is most dangerous due to ocular involvement. The most serious complication if untreated is:
37. A 55-year-old woman presents with tense blisters on erythematous plaques over the trunk and limbs. Biopsy shows a subepidermal bulla with eosinophils. Direct immunofluorescence (DIF) demonstrates linear IgG and C3 along the basement membrane zone. The target antigen is most likely:
38. A patient with pemphigus vulgaris undergoes salt-split skin test using the patient's serum. The antibodies are found to bind to the:
39. A 35-year-old woman with celiac disease develops intensely pruritic papulovesicles symmetrically distributed over extensor surfaces of elbows and knees. Perilesional DIF shows granular IgA deposits in dermal papillae. The autoantigen is:
40. Paraneoplastic pemphigus (PNP) most characteristically shows which unique DIF pattern that distinguishes it from other pemphigus variants?
41. A 60-year-old man develops painful oral erosions, haemorrhagic crusting of lips, and flexural blisters. Biopsy reveals suprabasal acantholysis with tombstone appearance. DIF shows intercellular IgG in the epidermis. Which Desmoglein pattern best explains both mucosal and skin involvement?
42. Linear IgA bullous dermatosis (LABD) in adults most characteristically shows which clinical distribution pattern that distinguishes it from bullous pemphigoid?
43. A renal transplant recipient on mycophenolate mofetil develops tense blisters; biopsy shows subepidermal bulla with neutrophils. DIF shows linear IgG at BMZ. Indirect IF on salt-split skin shows fluorescence on the dermal floor. The likely diagnosis is:
44. A 45-year-old woman presents with tense bullae predominantly on the inner thighs, flexures, and abdomen. The Nikolsky sign is negative. DIF of perilesional skin shows linear IgG and C3 at the BMZ. ELISA is positive for anti-BP180 NC16A domain antibodies. Which autoantigen is targeted in the transmembrane collagenous domain responsible for triggering the complement pathway?
45. A new drug — rituximab — has been approved as first-line therapy for moderate-to-severe pemphigus vulgaris. The mechanism by which rituximab achieves remission in pemphigus is:
46. A 70-year-old man develops tense bullae and erosions exclusively on oral mucosa, conjunctiva, and nasopharynx. Skin is spared. DIF shows linear IgG and C3 at BMZ. Anti-laminin-332 antibodies are detected. Which systemic complication requires urgent investigation?