Ependymosarcoma harboring C11orf95:RELA fusion transcript: Report of two cases and review of the literature.

Ependymoma is a relatively rare glial tumor of the central nervous system that arise from the cells lining the ventricles and central canal of the spinal cord. Ependymosarcoma (ES) is a newly introduced tumor entity of uncertain prognosis characterized by a rare phenomenon of a malignant mesenchymal transition arising within an ependymoma. ESs are surgically challenging tumors for diagnosis and therapy with a high incidence of morbidity and mortality. Here, we report two diagnostically challenging cases of primary ES in a 25-year-old female and a 17-year-old male. Both the cases presented with progressive and sequential neurological deficits over a period of five to eight months, and histological examination revealed a biphasic gliomesenchymal architecture comprised of anaplastic ependymomatous and sarcomatous components. Molecular genetic analysis revealed the presence of type 1 C11orf95:RELA fusion transcript. To date, 22 cases of ES have been reported in the literature, and only one case harbored type 1 C11orf95:RELA fusion transcript.