The fluorescence of melanocytic lesions.

The fluorescence of routine formalin-fixed sections of a variety of melanocytic lesions has been studied. The technique has value in distinguishing benign and atypical nevi from malignant melanomas. Forty-one of 48 melanomas exhibited positive fluorescence, whereas 15 of 86 of a variety of benign nevi were positive. The majority of the negative melanomas were Hutchinson's melanotic freckles, and the majority of the positive nevi were Spitz's nevi. Positive focal junctional fluorescence was a feature in up to half of the cases from established dysplastic nevus syndrome, but was noted only occasionally in sporadic dysplastic nevi. This distinguishes the dysplastic group from banal nevi and may be a marker of malignant potential. It is proposed that positive fluorescence is a marker of a melanocyte with an immature metabolic pathway.