Autofluorescence of fungi: an aid to detection in tissue sections.

Many pathogenic fungi have been found to autofluoresce in routine hematoxylin and eosin sections when exposed to ultraviolet light. These fungi include Blastomyces, Cryptococcus, Candida, Aspergillus, Coccidioides, and occasionally, Histoplasma. No autofluorescence was observed with Mucor. Examinations of other inflammatory processes, including those producing a granulomatous response, have not revealed any false-positive results. The advantages of fluorescent microscopy for fungal screening include: (1) no special staining procedures required; (2) no time delay, as involved with special stains; (3) the ability to scan sections at a relatively low power; and (4) the ability to tentatively identify the fungus. Disadvantages may include: (1) lack of a fluorescent microscope, and (2) a possible aging process whereby autofluorescence is lost in older cases.