Pathology · patient case question
Which diagnostic test confirms the diagnosis?
Patient case: Vesiculobullous Disease
demo: 55-year-old female
chief: “Spicy food burns terribly and my gums peel.”
history: Six-month history of oral ulceration preceding any skin involvement. No fever.
meds: None
findings: Diffuse buccal mucosal erythema with ragged erosions, desquamative gingivitis, and flaccid bullae that rupture readily. Gentle lateral pressure on adjacent normal-appearing mucosa produces a new blister.
Show answer and explanation
Correct answer: C. Biopsy of perilesional tissue submitted for direct immunofluorescence
- A. Culture addresses infection; this is an autoimmune disease.
- B. A CBC does not diagnose an autoimmune blistering disease.
- C. Correct. Perilesional tissue submitted in Michel's medium for direct immunofluorescence shows intercellular IgG and C3 in a fishnet pattern around keratinocytes — the diagnostic finding in pemphigus vulgaris.
- D. Cytology may show Tzanck cells but is not diagnostic and cannot distinguish pemphigus from viral acantholysis.
Note: Sampling perilesional — not ulcerated — tissue is critical; an ulcer base has already lost the epithelium that carries the diagnostic immune deposits.