Mohs surgery report: spindle cell fibrohistiocytic tumors: classification and pathophysiology.

Four patients with spindle cell cutaneous fibrohistiocytic neoplasms are presented. A classification scheme for this group of tumors is discussed along with the histologic and immunohistochemical criteria needed to establish the diagnosis. Cutaneous malignant fibrous histiocytoma (atypical fibroxanthoma) may behave biologically as a neoplastic rather than reactive mesenchymal tumor with definite invasive and metastatic potential.