A 38-year-old woman with known lichen planus develops tense vesicles and bullae arising both on her violaceous papules and on apparently normal skin. Direct immunofluorescence of perilesional skin shows linear deposition of IgG and C3 along the basement membrane zone. Which antigen is targeted in this condition?

• A Desmoglein 3
• B Type VII collagen
• C Transglutaminase 3
• D BP180 (type XVII collagen) ✓

Explanation

This is lichen planus pemphigoides, in which antibodies against BP180 (type XVII collagen), specifically the NC16A domain, develop secondarily in a patient with lichen planus, producing tense blisters on LP lesions and normal skin with linear IgG and C3 at the basement membrane zone. Desmoglein 3 indicates pemphigus vulgaris, transglutaminase 3 indicates dermatitis herpetiformis, and type VII collagen indicates epidermolysis bullosa acquisita, none of which show this linear BMZ pattern combined with pre-existing LP.

Reference: Rook's Textbook of Dermatology, 9th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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