A 68-year-old man develops large, tense, fluid-filled blisters over flexural surfaces of the arms and lower abdomen. Oral mucosa is spared. Histology shows a subepidermal blister with eosinophils, and direct immunofluorescence shows continuous linear IgG and C3 along the dermoepidermal junction. The autoantibody targets:

• A Type VII collagen anchoring fibrils
• B Desmoglein 3 of intercellular desmosomes
• C BPAG2 (BP180), a component of the hemidesmosome ✓
• D Keratin 14 intermediate filaments

Explanation

Bullous pemphigoid features IgG antibodies against BP180 (BPAG2) and sometimes BP230, both components of hemidesmosomes that anchor basal keratinocytes to the basement membrane. Antibody binding activates complement and recruits eosinophils whose proteases split the lamina lucida, producing tense subepidermal bullae. Desmoglein 3 (option B) is the target in pemphigus vulgaris, which produces flaccid intraepidermal blisters and oral involvement, distinguishing it clinically from this patient's presentation.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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