Abstract

The authors examined a case of Bednar tumor(pigmented dermatofibrosarcoma protuberans). A 35-year-old woman presented with protruding black back mass 3x2.5 cm in surface dimension and 1 cm in heigh, which has grown slowly for 30 years. Microscopically the lesion is characterized by spindle cells arranged in storiform pattern and admixed with melanin containing dendritic cells. Ultrastructural study revealed three cell populations: (1) cells resembling fibroblasts, (2) cells resembling perineural cells, and (3) melanocytes. The immunohistochemical study using S-100 protein alpha-1 antitrypsin, antichymotrypsin and EMA revealed negative reaction in spindle fibroblastic tumor cells. The histogenesis of this neoplasm remains controversial; neuroectoderm, perineural cell, fibroblast and histiocyte. Through the ultrastructural study and immunohistochemical study, the authors suggested that Bedner tumor arises form the neuroectoderm with bidirectional to perineural and fibroblastic differentiation.

• Keywords: Bednar tumor;Histogenesis;Neuroectoderm;Dermatofibrosarcoma protuberans