Prognostic significance of H3.K27me3 loss in CNS WHO grade 2 meningiomas: a multicentre clinicopathological study.

K27me3 loss was detected in 32 (29.4%) tumours and was significantly associated with older age (p = 0.034), higher mitotic index (p = 0.019), and necrosis (p = 0.005).

Inter-observer agreement for H3.

K27me3 scoring was substantial (κ = 0.77).

K27me3 loss (HR = 3.243, p < 0.001), subtotal resection (HR = 2.461, p = 0.013), and Ki-67 > 10% (HR = 2.136, p = 0.026) predicted shorter DFS.