Supratentorial extraventricular ependymal neoplasms: A clinicopathologic study of 32 patients

BACKGROUND. Published research on the clinicopathologic features of extraventricular ependymal neoplasms of the cerebral hemispheres has been scant. METHODS. Thirty-two archival cases were studied to investigate the prognostic impact of clinicopathologic parameters including flow cytometry, the proliferation (Ki-67) labeling index, and p53 expression. RESULTS. Among these 32 cases were 2 subependymomas, 19 ependymomas, and 11 anaplastic ependymomas. No significant gender predilection was observed, and 45% of patients were in their second or third decade of life. The left cerebral hemisphere was 1.5 times more commonly involved. On available imaging studies, lesions were often cystic, with or without a mural nodule. Tumors expressed glial fibrillary acidic protein (87%), S-100 protein (77%), cytokeratin (43%), and epithelial membrane antigen (17%). Ki-67 proliferation index paralleled tumor grade. Immunoreactivity for p53 protein was observed in the 2 cases of subependymoma, in 10 of 11 anaplastic ependymomas, and in 6 of 17 ependymomas. Flow cytometry performed in 27 tumors revealed diploidy in 20 cases and aneuploidy in 4 cases (3 anaplastic and 1 classic ependymomas), with S-phase fraction ranging from 0.2-9.7. Eleven subjects were additionally treated with radiotherapy, and 3 with chemotherapy. Follow up was available in 25 (78%) patients. CONCLUSIONS. The results of the current study suggest that there is no significant relation between histopathology, Ki-67 proliferation index, p53 immunolabeling, tumor ploidy, and biologic behavior.