The sensitivity and specificity of direct immunofluorescence testing in disorders of mucous membranes.

BACKGROUND: Direct immunofluorescence testing is frequently used to diagnose inflammatory mucosal disorders, but its accuracy relative to histologic and clinical diagnosis has not been reported.
OBJECTIVE: Our purpose was to compare diagnoses made on the basis of direct immunofluorescence, histologic features, and clinical impression and define optimal immunofluorescence criteria.
METHODS: Direct immunofluorescence findings and diagnostic impressions for 500 unselected mucosal biopsy specimens were recorded, as were the histologic diagnosis, initial clinical impression, and final diagnosis made on the basis of all studies and follow-up. Sensitivity and specificity were calculated for each parameter by diagnosis and site.
RESULTS: Direct immunofluorescence testing was superior for diagnosing pemphigus and pemphigoid and was slightly inferior to histologic evaluation for diagnosing lichen planus. Optimal criteria were IgG and C3 intercellular substance staining for pemphigus, linear C3 basement membrane zone deposits for pemphigoid, and shaggy fibrinogen basement membrane zone staining plus IgM cytoids for lichen planus. Direct immunofluorescence testing was diagnostic for several extraoral mucosal biopsy specimens.
CONCLUSION: Direct immunofluorescence is a valuable diagnostic tool for diseases of the oral mucosa and other mucosal sites.