A skin biopsy from a vesicle on the back shows linear IgG and C3 deposits along the basement membrane zone on direct immunofluorescence (DIF). Which layer does the blister form at on salt-split skin in bullous pemphigoid?

• A Within the sublamina densa (dermal side)
• B Within the lamina lucida (epidermal side) ✓
• C Intraepidermally above the basal layer
• D Within the stratum spinosum

Explanation

In bullous pemphigoid, autoantibodies target BP180 (collagen XVII) and BP230 in the hemidesmosome, located within the lamina lucida. On salt-split skin (1M NaCl splits at the lamina lucida), the immunoreactants are deposited on the epidermal side of the split. This distinguishes BP from epidermolysis bullosa acquisita (EBA) and anti-p200 pemphigoid, where deposits are on the dermal side of the salt-split. Pemphigus shows intraepidermal intercellular staining.

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.