Fibrous histiocytoma of the parotid gland

The light microscopic, electron microscopic, and immunocytochemical characteristics of a case of a fibrous histiocytoma arising in the parotid gland is presented. This neoplasm is very rare in this site and must be distinguished from other spindle cell tumors of the parotid gland, particularly those of epithelial and myoepithelial origins. Histologic characteristics similar to those displayed by dermatofibromas and dermatofibrosarcoma protuberans help to differentiate this tumor from other spindle cell tumors. The absence of cytochemical epithelial markers and the electron microscopic demonstration of fibroblasts and histiocytes are useful in establishing the diagnosis. This tumor, which was confined completely to the parotid gland, appears to have arisen from mesenchymal elements within the gland.