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:
- A Desmoglein-3
- B Envoplakin
- C BP180 (type XVII collagen) ✓
- D Desmoglein-1
Correct answer: C. BP180 (type XVII collagen)
Explanation
Bullous pemphigoid (BP) is caused by IgG autoantibodies against BP180 (type XVII collagen / BPAG2) and BP230 (BPAG1). Clinically it presents with tense blisters on an urticarial base; histology shows subepidermal bulla with eosinophils, and DIF shows linear IgG/C3 at the BMZ. Desmoglein-3 is the target in pemphigus vulgaris (intraepidermal split); Desmoglein-1 in pemphigus foliaceus; Envoplakin in paraneoplastic pemphigus.
Reference: Neena Khanna Illustrated Synopsis of Dermatology & STD, 6th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.