MKI67 and neoplasm: Other variables, including the cutoff of <4 and ≥4 for both mitoses per 10 high-power fields and the rate of proliferation as determined by estimation or quantification of immunolabeling with Ki-67, were based on the 2021 CNS WHO criteria for evaluation of Ki-67 as a marker of tumor aggressiveness and recurrence and the number of mitoses as diagnostic criteria involved in the grading of meningiomas (18).