An 80-year-old man develops tense pruritic bullae over flexural surfaces. Biopsy shows a subepidermal blister with eosinophils, and direct immunofluorescence demonstrates continuous linear deposits of IgG and C3 along the basement membrane zone. The autoantigen targeted is:

• A Desmoglein 3 in the stratum spinosum
• B BP180 (type XVII collagen), a transmembrane hemidesmosomal component ✓
• C Type VII collagen anchoring fibrils of the sublamina densa
• D Keratin 14 intermediate filaments of basal keratinocytes

Explanation

Bullous pemphigoid is caused by autoantibodies against BP180 (also called BPAG2 or type XVII collagen), a hemidesmosomal protein, producing a subepidermal split with tense bullae and linear IgG and C3 at the basement membrane. Desmoglein 3 defines pemphigus vulgaris, which shows intraepidermal acantholysis and flaccid bullae. Type VII collagen is the target in epidermolysis bullosa acquisita, which characteristically heals with scarring and milia.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.