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:

• A 180 kDa (BPAG2/collagen XVII) ✓
• B 130 kDa (desmoglein-3)
• C 160 kDa (desmoglein-1)
• D 230 kDa (BPAG1) alone

Explanation

Bullous pemphigoid involves autoantibodies against BPAG2 (BP180/collagen XVII, 180 kDa) and BPAG1 (BP230, 230 kDa), located in the hemidesmosome. The NC16A domain of BPAG2 is the immunodominant epitope. DIF shows linear IgG + C3 at the BMZ. While antibodies to both antigens occur, anti-BP180 (180 kDa) is more pathogenic and clinically relevant. BPAG1 alone does not cause the disease.

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.