Histologic prognostic factors in ependymoma

The prognostic value of a series of histologic signs and clinical features was studied in a series of 298 ependymomas, collected from different institutions. The distribution of tumor sites varied in relation to patient age, with infratentorial cases prevailing under 4 years. Life table univariate analysis demonstrated as highly significant prognostic factors: (1) the number of mitoses; (2) endothelial hyperplasia; (3) necrosis; (4) intracranial site; (5) age <4 years. Multivariate analysis by tumor site revealed mitoses cell density, age >16 years in supratentorial cases, and subependymoma in infratentorial cases to be prognostically important. Comparison of the anaplastic variant with the other tumor types in intracranial cases did not show a significant difference in survival even though the median survival time of anaplastic cases was shorter. The main conclusion is that the histological criteria employed to diagnose anaplasia in gliomas are not useful for recognizing anaplasia in ependymomas. The number of mitoses is a very important prognostic factor in supratentorial cases, whereas endothelial proliferations and necroses are much less important as prognostic factors than in gliomas.