The diagnostic value of fungal fluorescence in onychomycosis.

BACKGROUND

Fluorescence of pathogenic fungi has been previously shown when hematoxylin and eosin-stained sections are examined under a fluorescent microscope. We hypothesize that this phenomenon could aid in the evaluation of nail specimens for onychomycosis.

METHODS

Forty-eight routinely stained nail sections of periodic acid-Schiff (PAS)-positive onychomycosis, along with 23 PAS-negative control specimens with a clinical diagnosis of onychomycosis, were studied under a fluorescent microscope to determine the clinical usefulness of this technique.

RESULTS

In most cases, fluorescence of fungal organisms was noted. Fungi were identified by their tubular or annular shapes with fluorescence surrounding them. The sensitivity and specificity of the method were 96 and 90%, respectively. In some cases, it was difficult to identify the fungi because of the relative paucity of organisms, weak fluorescence and high background fluorescence of eosinophilic nail keratin.

CONCLUSIONS

We conclude that fluorescence microscopy can be used as a rapid screening tool for identification of fungi in nail specimens.