benign neoplasm subependymal glioma Subependymal astrocytoma NOS Rare, slow-growing, benign intraventricular tumors, often asymptomatic and discovered incidentally. The tumors are classified histologically as ependymomas and demonstrate a proliferation of subependymal fibrillary astrocytes among the ependymal tumor cells. (From Clin Neurol Neurosurg 1997 Feb;99(1):17-22) Subependymal astrocytoma WHO grade I Ependymal tumor MESH:D018315 DOID:4843 Glioma, Subependymal Sirarat Sarntivijai mixed subependymoma-ependymoma SNOMEDCT:4553004