"Clark/dysplastic" nevi with florid fibroplasia associated with pseudomelanomatous features.

Abstract

Melanocytic nevi may exhibit histologic features in common with cutaneous melanoma, creating diagnostic difficulties. We sought to assess the clinical behavior of melanocytic nevi with pseudomelanomatous features in association with dermal fibrosis. Forty-two melanocytic nevi with pronounced fibrosis and associated pseudomelanomatous changes were collected and studied clinically and histologically. The fibrosis was centrally located and laminated in appearance. It imparted a trizonal appearance: a junctional component with prominent single cells and/or irregular nests, underlying fibrosis, and a mature dermal component. No recurrence or metastases were evident over an average follow-up period of 2 years. The follow-up period was short. The central location and laminated appearance of the fibrosis suggest that this may represent the extreme end of a spectrum of fibroplastic changes in "Clark/dysplastic" nevi. Adjacent features of "Clark/dysplastic" nevi and limitation of pseudomelanomatous features to the perifibrotic focus are important in accurately identifying these lesions. Although melanocytic nevi with exaggerated fibroplasia may show foci with melanoma-like features, they do not appear to exhibit aggressive clinical behavior.