Proliferation patterns across meningioma locations: A WHO grade-based analysis

Meningiomas are the most common primary central nervous system tumors and their biological behavior is closely related to histopathological grade and proliferative activity. This study investigated the associations between World Health Organization (WHO) grade, tumor location, mitotic activity, and Ki-67 labeling index in previously untreated meningiomas. We retrospectively analyzed 298 surgically treated primary meningiomas diagnosed between 2013 and 2025, re-evaluated according to the 2021 WHO Classification of Central Nervous System Tumors. Mitotic counts and Ki-67 labeling indices were assessed in hotspot areas. Associations between proliferation markers, grade, and anatomical location were analyzed statistically, and receiver operating characteristic (ROC) analyses determined optimal cut-off values. Of the tumors, 55.0% were WHO Grade 1, 41.6% Grade 2, and 3.4% Grade 3. Both markers increased significantly with grade and showed a strong positive correlation (ρ = 0.79, P < .001). Convexity meningiomas were associated with higher grades and increased proliferative activity, whereas skull base and spinal tumors predominantly exhibited lower grades and lower proliferation indices. ROC analyses demonstrated comparable discriminatory performance for Ki-67 and mitotic counts across WHO grades. In summary, proliferation markers strongly correlate with WHO grade and vary by tumor location, supporting their combined value in meningioma risk stratification.