Ossifying fibromyxoid tumor of soft parts: evidence supporting Schwann cell origin.

Immunohistochemical and ultrastructural studies of an ossifying fibromyxoid tumor of soft parts have been performed. Immunoreactivity of neoplastic cells for S-100 protein and glial fibrillary acidic protein, lack of immunoreactivity for type II collagen, and presence of basal lamina indicate that the tumor is of Schwann cell and not cartilaginous origin.