A 50-year-old woman presents with flaccid, easily ruptured blisters on normal-appearing skin and mucous membranes. Tzanck smear shows acantholytic cells. DIF shows intercellular IgG in a 'fish-net' pattern throughout the epidermis. The target antigen is:

• A Desmoglein-3 (Dsg-3) alone or with Dsg-1 ✓
• B Desmoglein-1 (Dsg-1)
• C BP180 (type XVII collagen)
• D Epidermal transglutaminase (TG3)

Explanation

Pemphigus vulgaris (PV) is caused by IgG autoantibodies primarily against desmoglein-3 (Dsg-3). Mucosal-dominant PV has antibodies to Dsg-3 alone; mucocutaneous PV has antibodies to both Dsg-3 and Dsg-1. The DIF pattern — intercellular IgG and C3 in a 'fish-net' (chicken-wire) pattern throughout the epidermis — is pathognomonic of PV. Dsg-1 antibodies alone cause pemphigus foliaceus (superficial blisters, no mucosal involvement). BP180 is the target in bullous pemphigoid. TG3 is targeted in dermatitis herpetiformis.

Reference: Neena Khanna Illustrated Synopsis of Dermatology & STD, 6th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.