Histopathologic features and MIB-1 labeling indices in recurrent and nonrecurrent meningiomas

Background.-Predicting the behavior of meningiomas based on histopathologic features alone has remained problematic. Design.-This study retrospectively compared several histopathologic feature s and MIB-1 labeling indices (LIs) in recurrent meningiomas with those of n onrecurrent meningiomas. Six histopathologic features, including mitoses, n ecrosis, loss of architectural pattern, hypervascularity/hemosiderin deposi tion, prominent nucleoli, and nuclear pleomorphism, were compared between 3 2 recurrent and 27 nonrecurrent meningiomas using Fisher exact tests. MIB-1 LIs (% positive tumor cell nuclei) were compared using the Wilcoxon rank s um test. Results.-The patients in the recurrent group included 26 women (mean age, 5 5 years), who developed 1 to 5 recurrences. Time intervals to the first rec urrence ranged from 5 to 183 months (mean, 55 months). The nonrecurrent gro up included 21 women (mean age, 56 years), with follow-up ranging from 88 t o 124 months (mean, 109 months). Of the histopathologic features evaluated, statistically significant differences between the recurrent and nonrecurre nt groups were found only with respect to prominent nucleoli (P = .024) and nuclear pleomorphism (P < .001), both of which were more common in the rec urrent group. In the recurrent group, 9 tumors were considered malignant (d efined by brain invasion or metastasis) versus 2 of the nonrecurrent mening iomas. Nineteen percent of nonrecurrent tumors versus 41% of recurrent tumo rs had 2 or more of the 6 histopathologic features. MIB1 LIs in the nonrecu rrent group ranged from 0 to 8.3 (mean, 1.5) and were generally lower than those in the recurrent group (range, 0-32.5; mean, 5.4); no statistical dif ference was identified between these groups. No statistically significant d ifference with regard to histology or MIB-1 ils was noted between the initi ally excised recurrent tumor and the most recently resected recurrence. Conclusions.-Of the histopathologic features examined, only prominent nucle oli and nuclear pleomorphism were found to be statistically more common in recurrent than nonrecurrent meningiomas. The mean MIB-1 LI was higher in th e recurrent than in the nonrecurrent group, although there was no statistic al difference between means and there was clear overlap with regard to MIB- 1 LI ranges.