Malignant (Anaplastic) Meningioma

Malignant meningioma (anaplastic meningioma) is a WHO grade 3 meningeal tumor representing approximately 1-3% of all meningiomas. While the vast majority of meningiomas are benign (grade 1) or atypical (grade 2), grade 3 tumors are clinically aggressive with high recurrence rates and the potential for distant metastases (rare for meningiomas).

Histological criteria for grade 3 meningioma include features of frank malignancy resembling carcinoma, sarcoma, or melanoma, or a markedly elevated mitotic rate (20 or more per 10 high-power fields). The 2021 WHO classification incorporates molecular features such as TERT promoter mutations and CDKN2A/B homozygous deletion as criteria for grade 3 designation, even in tumors with lower mitotic rates.

Treatment requires multimodal management with maximal safe resection followed by adjuvant radiation. Despite aggressive treatment, recurrence is common and median survival is significantly shorter than for benign meningiomas. Systemic therapy options are limited but include hydroxyurea, somatostatin analogs, and emerging targeted therapies for specific molecular alterations. Repeated surgery and radiation are often required for recurrent disease.