ABSTRACT
Subependymoma Subependymomas are low-grade intraventricular tumors, usually found in the IVth ventricle and, less frequently, in the lateral ventricle. They may be multiple. Their cell of origin is unknown. They were named because of their histologic resemblance to areas of tumor sometimes found in ependymomas. However, cytogenetic studies of subependymoma give a normal karyotype.130 When they cause symptoms, they usually do so by ventricular obstruction, but many are asymptomatic, encountered incidentally at autopsy, or when a scan is done. The tumors are iso-to hypointense on T1 and may be heterogeneous due to calcification and/or hemorrhage. Some contrast enhance. Histologically, clusters of GFAP-and S100-positive monomorphic cells are found in a fibrillary background; sclerotic vessels and nuclear pleomorphism may be found, but mitotic figures, vascular proliferation and necrosis are absent and the MIB-1 labeling index is lower than that of other ependymal tumors.131 If symptomatic, surgery is curative.
