Ependymoma of the uterosacral ligament.

Extraspinal ependymomas have been described in the subcutaneous sacrococcygeal and presacral areas. Since 1984, eight pelvic ependymomas have been reported that have originated in the ovary, broad ligament, mesovarium, and omentum. This report documents an additional case arising from the right uterosacral ligament in a 48-year-old woman. The diagnosis of ependymoma was supported by a histologic pattern of true rosettes and pseudo-rosettes, glial fibrillary acidic protein (GFAP) positivity, and electron microscopic findings of cilia, blepharoplasts, and intermediate filaments. The tumor was positive for cytokeratin and vimentin. Ultrastructurally, neurosecretory granules were present within the cytoplasm. These features have not been described previously in pelvic ependymomas. These tumors, although easily confused with serous papillary carcinoma, should be distinguished from serous papillary carcinoma because of their apparently better prognosis and tendency for late recurrence.