The use of Calcofluor white in the histopathologic diagnosis of oral candidiasis.

Abstract Calcofluor white (CW) is a water-soluble, colorless dye that selectively binds to beta 1–4 polysaccharides (cellulose) in fungal cell walls. The planar, trans-form of the molecule fluoresces light blue when exposed to UV light (345 to 365 nm). Recuts of all biopsy specimens, accessioned over a 6-month period, that had been stained with Grocott's methenamine silver (GMS) were stained with CW and examined. Of the 34 cases from which specimens were reviewed, 17 had specimens that were positive for the presence of fungal organisms as indicated by both GMS and CW staining. Specimens from all of the 17 remaining cases were negative for the presence of fungal organisms, as staining with both GMS and CW indicated. Similar results were obtained with direct fungal smears. The CW technique has significant advantages over traditional methods, including rapidity, cost, sensitivity, simplicity, and absence of interference with permanent fungal stains.