Anaplastic oligoastrocytoma (WHO grade III) is a more poorly differentiated tumor than oligoastrocytoma. These types of tumors accounted for 4% of tumors in a large series of supratentorial anaplastic gliomas in adults. The mean age of patients has been reported to be 45 years. Anaplastic oligoastrocytomas are predominantly hemispheric tumors, and the frontal lobes are more commonly involved than the temporal lobes. These tumors share many genetic alterations that are also implicated in the progression of astrocytomas and oligodendrogliomas. The prognosis of patients with anaplastic oligoastrocytomas is relatively poor though considerably better than for patients with glioblastoma.
(Refer to the Mixed Gliomas section of this summary for treatment information.)
Myxopapillary ependymoma (WHO grade I) is a slow-growing astrocytic tumor, histologically characterized by tumor cells arranged in a papillary pattern around vascularized mucoid stromal cores. In a large series of cases of ependymal tumors, 13% were found to be of the myxopapillary type. The average age at presentation is approximately 36 years. This tumor almost exclusively occurs in the conus-cauda-filum terminate region of the spinal cord. No specific cytogenetics or molecular genetics exist with this tumor. The prognosis for patients with myxopapillary ependymoma is good with the possibility of more than 10 years of survival after total or partial resection.
Subependymoma (WHO grade I) is a slow-growing glial neoplasm that is typically attached to the ventricular wall. In a large series of cases, this histologic type accounted for 8.3% of ependymal tumors. This tumor occurs most frequently in middle-aged and elderly males. Consistent cytogenetic abnormalities have not been found. Subependymoma carries a good prognosis; surgical removal is usually curative.
Ependymoma (WHO grade II) is a slow-growing tumor of children and young adults that originates from the wall of the cerebral ventricles or from the spinal canal and is composed of neoplastic ependymal cells. These types of tumors account for 3% to 5% of all neuroepithelial tumors and for 30% of those in children younger than 3 years. Ependymomas are the most common neuroepithelial neoplasms in the spinal cord and comprise 50% to 60% of spinal gliomas. These tumors occur at any site in the ventricular system and in the spinal canal; they develop most commonly in the posterior fossa and in the spinal cord, followed by the lateral ventricles and the third ventricle. Histologic variants include cellular ependymoma, papillary ependymoma, clear cell ependymoma, and tanycytic ependymoma. Almost 33% of ependymomas involve aberrations of chromosome 22. These types of tumors contain no specific genetic alterations. Spinal ependymomas are a primary manifestation of neurofibromatosis type 2 (NF2), which indicates a possible role for the NF2 gene in these neoplasms. In a series of adult patients with ependymoma, survival rates at 5 and 10 years were approximately 57% and 45%, respectively.