A 68-year-old man develops multiple tense, fluid-filled bullae over flexor surfaces of the arms and lower abdomen. Some arise on apparently normal skin, others on erythematous bases. Biopsy shows a subepidermal blister with eosinophils, and direct immunofluorescence reveals linear IgG and C3 along the basement membrane zone. The target antigen lies within:
- A BP180 (type XVII collagen) of the hemidesmosome anchoring basal keratinocytes ✓
- B Desmogleins 1 and 3 of epidermal intercellular desmosomes
- C Type VII collagen anchoring fibrils beneath the lamina densa
- D Laminin 332 of the lamina lucida associated with mucosal scarring
Correct answer: A. BP180 (type XVII collagen) of the hemidesmosome anchoring basal keratinocytes
Explanation
Bullous pemphigoid is caused by IgG against BP180 (and BP230) hemidesmosome components, producing a subepidermal blister with eosinophils and linear basement membrane IgG and C3; loss of hemidesmosomal attachment separates the entire epidermis from dermis, hence tense bullae. Desmoglein antibodies cause pemphigus vulgaris with intraepidermal acantholysis and flaccid bullae, the key distractor killed by the subepidermal split and tense blister morphology.
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.