Ovarian ependymoma: Appearance on magnetic resonance imaging

Primary Glial and Neuronal Tumors of the Ovary or Peritoneum: A Clinicopathologic Study of 11 Cases

Primary glial and neuronal tumors of the ovary or peritoneum are rare neuroectodermal-type tumors similar to their counterparts in the central nervous system. We retrospectively reviewed 11 cases. These cases included 4 ependymomas, 6 astrocytic tumors, and 1 neurocytoma. Patients' age ranged from 9 to 50 years (mean, 26 y; median, 24 y). All ependymal tumors with detailed clinical history (n=3) were not associated with any other ovarian neoplasm. In contrast, all astrocytic tumors were associated with immature teratoma (n=4), mature cystic teratoma (n=1), or mixed germ cell tumor (n=1). The neurocytoma arose in association with mature teratomatous components in a patient with a history of treated mixed germ cell tumor. Immunohistochemical staining showed that 7 of 7 ependymal and astrocytic tumors (100%) were positive for glial fibrillary acidic protein, and 2 of 2 ependymomas (100%) were positive for both estrogen and progesterone receptors. The neurocytoma was positive for synaptophysin and negative for S100 protein, glial fibrillary acidic protein, and SALL4. No IDH1-R132H mutation was detected in 2 of 2 (0%) astrocytomas by immunohistochemistry. Next-generation sequencing was performed on additional 2 ependymomas and 2 astrocytomas but detected no mutations in a panel of 50 genes that included IDH1, IDH2, TP53, PIK3CA, EGFR, BRAF, and PTEN. Follow-up information was available for 8 patients, with the follow-up period ranging from 4 to 59 months (mean, 15 mo; median, 8.5 mo), of which 3 had no evidence of disease and 5 were alive with disease. In conclusion, primary glial and neuronal tumors of the ovary can arise independently or in association with other ovarian germ cell tumor components. Pathologists should be aware of these rare tumors and differentiate them from other ovarian neoplasms. Even though an IDH1 or IDH2 mutation is found in the majority of WHO grade II and III astrocytomas, and in secondary glioblastomas arising from them, such mutations were not identified in our series, suggesting that these tumors are molecularly different from their central nervous system counterparts despite their morphologic and immunophenotypic similarities.