Expression of the intermediate filament peripherin in skin tumors.

Peripherin is a neuronal intermediate filament reportedly expressed in neuroendocrine skin carcinomas and some melanocytic tumors. In order to assess the diagnostic usefulness of antibodies to peripherin in dermatopathology, we studied its expression in 68 skin tumors mostly of neural origin, and compared this expression with that of neurofilaments, a well-established neuronal marker. Antibodies to peripherin and neurofilaments both labeled dermal neurons present in normal skin and within the tumors. Specific labeling of tumor cells for peripherin was seen in only 2/5 neuroendocrine skin carcinomas, 3/18 benign nevi and 7/19 melanomas; even in these cases the percentage of tumor cells did not exceed 20%. We conclude that antibodies to peripherin may be used for the demonstration of cutaneous neurons in normal and diseased skin; however their diagnostic usefulness appears limited, less than that of antibodies to neurofilaments.