Pathologic Predictors of Local Recurrence in Atypical Meningiomas Following Gross Total Resection

To assess the local recurrence rate of gross totally resected atypical meningiomas and evaluate for pathologic predictors of recurrence.

All patients meeting the 2016 World Health Organization grade 2 meningioma criteria who received gross total resection were included in this retrospective analysis. A neuropathologist re-reviewed all surgical specimens for the following pathologic factors: brain invasion, macronuclei, necrosis, sheeting architecture, hypercellularity, high nuclear to cytoplasmic ratio, Ki67 proliferative index, mitotic number, and choroid or clear cell histology. Local recurrence and salvage therapy were recorded.

Ninety-seven patients met the inclusion criteria and had a median radiographic follow-up of 53 months (range, 3-153). Necrosis was present in 41 specimens (42%), and brain invasion occurred in 30 (31%). Seventy-six patients (78%) had 3 of 5 World Health Organization grade 2 qualifying atypical features. Median mitotic number and Ki67 index were 3 (0-12) and 15 (2%-55%), respectively. Only Ki67 proliferative index and mitotic number predict for local recurrence. The Kaplan-Meier estimate of local recurrence was 30.3% at 3 years.

In this cohort of gross totally resected atypical meningioma followed with observation, local recurrence occurred in 30.3% at 3 years. Ki67 index and mitotic number predict for local failure and could help stratify patients who would benefit from adjuvant therapy.