Salt-split skin indirect immunofluorescence is performed on serum from two patients with subepidermal blistering disorders. In patient 1, IgG binds to the floor of the artificial blister; in patient 2, IgG binds to the roof. Patient 2 most likely has which disorder?

• A Epidermolysis bullosa acquisita
• B Anti-p200 pemphigoid
• C Bullous systemic lupus erythematosus
• D Bullous pemphigoid ✓

Explanation

In salt-split skin, the lamina lucida splits so the hemidesmosomal antigen BP180 remains on the roof, giving roof binding in bullous pemphigoid. Type VII collagen anchors below the lamina densa and stays on the floor, so epidermolysis bullosa acquisita and bullous lupus erythematosus show floor binding. This test distinguishes them when both present as tense blisters with positive Nikolsky sign in older adults.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.