To depict the outcome of patients with WHO grade III meningioma and identify factors that may influence the survival.

Between 1989 and 2007, a retrospective search identified 43 WHO grade III meningiomas after cases exclusion. Nine patients (39.5%) had a previous history of grade I or II meningioma. The patients underwent a total of 89 surgical resections and 83.7% received radiotherapy. Median follow-up was 7.4 years.

At the end of the study, 35 patients were deceased (81.4%). One patient died of disseminated metastatic disease of a papillary meningioma. Median overall survival was 4.1 years, 95% CI [1.9, 8.3]. Overall survival probability at 1, 5 and 10 years were respectively: 81.4%, 95% CI [70.6, 93.9], 48.8%, 95% CI [36,66.3] and, 27.5%, 95% CI [16.9, 44.9]. In univariate Cox regression, a previous surgery for WHO grade I or II meningioma (HR=2.05, 95% CI [1.03, 4.07], P=0.04) and the mitosis count (HR=0.3, 95% CI [0.12, 0.79], P=0.02) were associated with the overall survival. However, neither macroscopic gross total resection (HR=0.87, 95% CI [0.4, 1.87], P=0.71), nor radiotherapy (HR=0.75, 95% CI [0.31, 1.83], P=0.53) was associated with an increased survival.

This series highlights the poor prognosis associate with the diagnosis of malignant meningioma. Patients with primary WHO grade III meningioma demonstrating less than 14 mitosis per 10 high power fields may live longer. We could not confirm the usefulness of complete resection and adjuvant radiotherapy.