EPENDYMOMA OF THE OVARY - A CASE-REPORT WITH IMMUNOHISTOCHEMICAL, ULTRASTRUCTURAL, AND DNA CYTOMETRIC FINDINGS, AS WELL AS HISTOGENETIC CONSIDERATIONS

Ovarian and paraovarian ependymomas are rare. This report presents the case of a 68-year-old woman with a stage la ependymoma of the ovary. The histologic picture was similar to that of ependymomas of the centr al nervous system. Immunohistochemical, electron microscopic, and DNA flow cytometric studies were performed from formalin-fixed, paraffin-e mbedded tissue. The diagnosis was supported by positive staining of cy toplasmic processes for glial fibrillary acidic protein. Immunoreactiv ity for vimentin, neuron-specific enolase, S-100, epithelial membrane antigen, and cytokeratin was also demonstrated. Ultrastructural examin ation revealed the presence of cilia on the surface of cysts and withi n intracellular lumina, abundant intermediate filaments in cytoplasmic processes, and intercellular junctions. The tumor displayed a diploid DNA content by flow cytometry. The histogenesis of ovarian ependymoma s is uncertain but may include an origin from a preexisting ovarian te ratoma or neometaplasia of mullerian duct-derived tissue.