An Unusual Case of Sarcoma Developing in a Previously Diagnosed Ependymoma-Case Report

Ependymomas are rare glial tumors arising from the ependymal cells lining the ventricles of central nervous system. It accounts for only 1.8% of all adult brain tumors. Gliosarcoma is a rare primary brain tumour composed of both malignant glial and sarcomatous components. Under the WHO classification, conventional gliosarcomas are considered a subtype of glioblastoma, an astrocytic tumor. We present a case of sarcoma developing in a patient previously diagnosed as ependymoma. Both the initial supratentotrial ependymoma and subsequent sarcoma are thought to have type 1 C11orf95-RELA fusion. This conclusion is supported by the finding of identical genetic alterations in both tumor elements. The term ependymosarcoma was first coined by Rodriguez F, et al. who described 11 cases of ependymal tumors with sarcomatous features. To date, 19 cases of ependymal tumors classified as WHO Grade II or III with sarcomatous changes have been published in the literature, with 10 of these cases occurring at recurrence. Genetic and mutational analyses have shown that identical genetic mutations occur in both the glial and sarcomatous tissues. This indicates that, though histologically distinct, the two components have a common genetic origin, favoring a monoclonal origin for both components.