Parachordoma of the sacrococcygeal region--a neuroepithelial tumor.

The parachordoma is a seldom, benign tumor of uncertain histogenesis. A case in a 25-year-old man is presented. The parachordoma in the present study reacted with antibodies to GFA, S-100, NSE and vimentin, but not with antibodies to EMA, keratin and NF. Differential diagnoses are the chordoma, the extraskeletal myxoid chondrosarcoma and the subcutaneous sacrococcygeal myxopapillary ependymoma. The immunohistochemical reactions of these tumors were compared and we found that the parachordoma had an immunologically different staining pattern. The parachordoma is thus immunologically different from the chordoma, the extraskeletal myxoid chondrosarcoma and the subcutaneous sacrococcygeal myxopapillary ependymoma. We conclude that the parachordoma is an entity of its own. The immunohistochemical reactions indicate that the parachordoma is a neuroepithelial tumor with glial differentiation.