Primary Ovarian Ependymoma: A Diagnostic Challenge Resolved by Immunohistochemistry. A Case Report

Primary ovarian ependymoma is an exceptionally rare tumor, a distinct nosological entity separate from central nervous system metastases, for which no standardized therapeutic recommendations exist. We report the case of a 25-year-old young woman admitted with abdominal and pelvic pain, in whom a computed tomography (CT) scan revealed a large bilateral ovarian tumor mass. Microscopic examination of the resection specimens, with confirmation by an expert reference center, revealed characteristic micro- and macrofollicular architecture associated with numerous ependymal-like rosettes. Immunohistochemical studies showed positivity for glial fibrillary acidic protein (GFAP), estrogen receptors (ER), and progesterone receptors (PR), focal expression of epithelial membrane antigen (EMA), and a Ki-67 proliferation index of 10%. Classified as stage III bilateral ovarian ependymoma, the patient underwent cytoreductive surgery followed by adjuvant chemotherapy. This case illustrates that, although exceptionally rare, primary ovarian ependymoma must be considered a differential diagnosis in young women presenting with an ovarian mass, and highlights the crucial role of collaboration with expert pathology reference centers for an accurate diagnosis.