Grading of oligodendrogliomas.

The purpose of this study was to determine the effectiveness of histologic grading of oligodendrogliomas in a retrospective study. 323 cases with adequate clinical information and confirmatory histological material were acquired from the files of the AFIP. A grading system was devised using the following criteria: endothelial proliferation, necrosis, nuclear/cytoplasmic ratio, cell density and pleomorphism. The grading system separated 23% of the cases into grade A, 49% into grade B, 22% into grade C and 6% into grade D. Statistical analysis showed that the grading system significantly correlated with survival (P less than or equal to 0.01). Median survival periods for each grade were as follows: grade A, 94 months; grade B, 51 months; grade C, 45 months; grade D, 17 months. Of the five factors comprising grade, only pleomorphism was significantly correlated with survival by itself (P less than or equal to 0.01). It is concluded that grading of this form of glioma can be an effective estimate of prognosis.