2016 Volume 126 Issue 12 Pages 2281-2286
We report a case of 40-year-old woman with a Bednar tumor arising on the upper left chest. The lesion was a 45×21 mm, slightly reddish plaque with bluish pigmentation in some areas. A wide local excision followed by split-thickness skin graft was performed. Histopathological examination of the resected specimen revealed proliferation of spindle-shaped cells arranged in a tight storiform pattern, admixed with melanin containing dendritic cells. In the lower part of the tumor, sinusoid-like slits lined by the pleomorphic cells were seen. Scattered multinucleated giant cells were also observed. Immunohistochemically, most of the spindle-shaped cells were positive for CD34 and negative for S-100 protein. The melanin containing dendritic cells were positive for S-100 protein. Cytogenetic analysis identified a gene fusion of exon 2 of platelet-derived growth factor beta (PDGFβ; 22q13) to exon 34 of collagen type I alpha 1 (COL1A1; 17q22). The present case demonstrates a close histogenetic relationship between Bednar tumor and giant cell fibroblastoma.
