Pleomorphic fibroma of the skin, a form of sclerotic fibroma: an immunohistochemical study.

We report a new case of pleomorphic fibroma of the skin arising on the face. The lesion was polypoid and fibrous, located on the dermis, and formed by coarse collagen bundles with sparse cells. It was also characterized by the presence of cellular atypia and pleomorphism without mitosis. Immunohistochemistry showed staining for vimentin and actin and negativity for S-100, CD34, CD68, alpha-1-antichymotrypsin and alpha-1-antitrypsin antigens, supporting a myofibroblastic origin. A few isolated cells also showed granular cytoplasmic detection of factor XIIIa. Although the disorder has been previously considered to be a tumour of preferential localization on the trunk or extremities, this does not always hold true as four of the 14 reported cases arose on the head. Pleomorphic fibroma is a benign condition and is we believe a variant of sclerotic fibroma.