A patient presents with widespread mucosal blistering and ulceration suggestive of mucous membrane pemphigoid. Which biopsy technique is MOST appropriate?

Correct answer: A. Incisional biopsy taken from the intact tissue at the edge of the lesion

• A. Correct. For vesiculobullous disease the specimen must include INTACT epithelium showing the plane of separation — so an INCISIONAL sample is taken from the raised, non-denuded tissue at the lesion margin (a perilesional biopsy). A second sample in Michel's transport medium is submitted for direct immunofluorescence, which shows linear IgG/C3 at the basement membrane in MMP.
• B. The center of an ulcer is denuded — there is no epithelium left to show the level of separation, so the specimen is non-diagnostic. This is the single most common biopsy error in vesiculobullous disease.
• C. The lesions are widespread; excision of the whole area is neither feasible nor necessary, and the diagnosis only requires a representative sample.
• D. Cytology samples surface cells only and cannot demonstrate the epithelial-connective tissue separation that defines these diseases.