Which immunobullous disorder classically shows a positive Nikolsky sign at the periphery of active blisters?

• A Epidermolysis bullosa acquisita
• B Bullous pemphigoid
• C Dermatitis herpetiformis
• D Pemphigus vulgaris ✓

Explanation

Pemphigus vulgaris produces suprabasal acantholysis, so the epidermis shears easily with tangential pressure, giving a positive Nikolsky sign during active disease. In bullous pemphigoid the split is subepidermal and the dermis remains firmly attached to the overlying epidermis, so Nikolsky sign is typically negative. Dermatitis herpetiformis has dermal papillary neutrophilic microabscesses with intact epidermis, and epidermolysis bullosa acquisita splits below the lamina densa, neither producing the superficial friability seen in pemphigus.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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