A 68-year-old woman develops tense bullae over flexor surfaces and lower abdomen without oral involvement. Biopsy shows a subepidermal blister with eosinophils. Direct immunofluorescence shows continuous linear IgG and C3 along the dermoepidermal junction. The target antigen is located in:

• A Desmoglein 3 of epidermal intercellular desmosomes
• B Keratin 5 of basal keratinocyte intermediate filaments
• C Type VII collagen of the sublamina densa anchoring fibrils
• D BP180 (type XVII collagen) of the hemidesmosomal anchoring complex ✓

Explanation

Bullous pemphigoid is driven by IgG against BP180 (and BP230) within the hemidesmosomes that tether basal keratinocytes to the basement membrane. Complement activation recruits eosinophils whose proteases split the lamina lucida, producing tense subepidermal bullae with linear IgG and C3 on immunofluorescence. Desmoglein targets produce intraepidermal acantholytic blisters in pemphigus, type VII collagen is the antigen in epidermolysis bullosa acquisita, and keratin 5 mutations cause inherited epidermolysis bullosa simplex.

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.