A Case of Primary Ovarian Primitive Neuroectodermal Tumor.

Primitive neuroectodermal tumors (PNET) are a family of poorly differentiated malignant neoplasms of neuroectodermal origin. According to the location of origin, PNETs could be further categorized as central or peripheral. Peripheral PNET (pPNET) is an uncommon type that accounts for 1% of all soft tissue sarcomas and occurs outside the central and sympathetic nervous systems. Ovarian PNET is a very rare tumor with a high mortality rate. We report a case of pPNET originating from the pelvic cavity of a young woman. Ultrasound and Magnetic Resonance Imaging (MRI) findings demonstrated the presence of a high-grade malignant ovarian tumor. On microscopic evaluation, the tumor was composed of solid nests and sheets of small rounded cells, and on Immunohistochemical (IHC) evaluation, the tumor cells showed intense cell-membranous immunoactivity for MIC2 protein (CD99). In the differential diagnosis of any invasive pelvic tumor in young women, pPNET should be considered.