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Pathology · single question

To confirm the diagnosis of desquamative gingivitis caused by mucous membrane pemphigoid (MMP), where should the biopsy be taken?

  1. From the center of the lesion
  2. Brush biopsy of the lesion surface
  3. From the most severely affected area
  4. From the perilesional (normal-appearing tissue adjacent to the lesion)
Show answer and explanation

Correct answer: D. From the perilesional (normal-appearing tissue adjacent to the lesion)

  • A. The center of an MMP lesion is often necrotic, ulcerated, or has lost epithelium — making histopathology and DIF results unreliable.
  • B. Brush biopsy (exfoliative cytology) collects surface cells and cannot assess basement membrane pathology or subepithelial antibody deposition.
  • C. The most severely affected areas are typically ulcerated/eroded — same problem as the lesion center; insufficient epithelium for DIF.
  • D. CORRECT. For MMP diagnosis, the PERILESIONAL biopsy technique is critical. The biopsy should be taken from the EDGE of the lesion — including some normal-appearing tissue — because: (1) the center of bullous/vesicular lesions often has no intact epithelium for histopathology; (2) direct immunofluorescence (DIF) requires intact epithelium to show IgG/IgA/complement deposition at the basement membrane zone (BMZ), which is best preserved in perilesional tissue.

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