Nerve sheath myxoma (neurothekeoma)--a case report.

A case of nerve sheath myxoma also called as neurothekeoma in a 33-year-old woman is described. The lesion appeared as a painful, elevated nodule on the scalp for several months, without an appreciable increase in size. Microscopically, it showed typical histologic characteristics of nerve sheath myxoma, and tumor cells revealed strong, positive reaction for S-100 protein and negativity for epithelial membrane antigen (EMA) on immunohistochemical staining. These immunohistochemical findings of this case support the view that the origin cells of this tumor may be schwann cells rather than perineurial cells. The histogenesis and differential diagnosis of this tumor are discussed.