Pathology · single question
For pemphigus vulgaris, which biopsy technique would be most appropriate to establish a definitive diagnosis?
Show answer and explanation
Correct answer: A. Direct immunofluorescence
The GOLD STANDARD for diagnosing pemphigus vulgaris is DIRECT IMMUNOFLUORESCENCE (DIF). A perilesional tissue sample is stained with fluorescent antibody probes to detect the IgG autoantibodies bound to desmoglein-1 and desmoglein-3 in the intercellular substance between keratinocytes (fishnet/chicken wire pattern). DIF confirms the specific immune-mediated nature of the disease and distinguishes PV from other blistering diseases.
- A. CORRECT. Direct immunofluorescence (DIF) is the definitive diagnostic technique for pemphigus vulgaris. It detects IgG deposits at the desmosomes in a characteristic 'fishnet' or 'chicken wire' pattern around keratinocytes.
- B. INCORRECT. Excisional biopsy completely removes a lesion and is used for small, resectable lesions — not appropriate as the primary diagnostic biopsy for PV (H&E histology alone shows suprabasal cleavage but cannot differentiate all blistering diseases without DIF).
- C. INCORRECT. VELscope is a fluorescence visualization device for mucosal examination to detect potentially malignant changes — it is not used for immune-mediated blistering disease diagnosis.
- D. INCORRECT. Serum antibody testing (indirect immunofluorescence or ELISA) detects circulating anti-desmoglein antibodies and is useful for monitoring disease activity, but is not the primary biopsy technique.