A 28-year-old man presents with painful oral erosions and flaccid bullae on the trunk. Direct immunofluorescence of a perilesional skin biopsy shows intercellular deposition of IgG in the epidermis. Which target antigen is most likely involved?

• A Desmoglein 3 ✓
• B BP180 (Collagen XVII)
• C Laminin 332
• D Type VII collagen

Explanation

The intercellular ('chicken-wire') IgG pattern on direct immunofluorescence is diagnostic of pemphigus. The patient has both mucosal (oral) and cutaneous involvement. In pemphigus with mucosal dominance, desmoglein 3 (Dsg3) is the primary target antigen. Desmoglein compensation theory explains that Dsg3 alone maintains mucosal adhesion, so anti-Dsg3 antibodies produce mucosal erosions. BP180 and type VII collagen are targets in bullous pemphigoid and epidermolysis bullosa acquisita, which show linear basement membrane zone staining.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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