True about meningiomas -

Meningiomas are tumors that arise from the dura mater and are composed of neoplastic (arachnoid cap ) cells. They are now the most common primary brain tumor, accounting for approximately 32% of the total . (this information has been added in 18th/e of Harrison). They tend to be more common in women and in patients with Neurofibromatosis type-2. Meningiomas are classified by the WHO into three histological grades of increasing aggressiveness: grade I or benign; grade II or atypical and grade III or malignant/anaplastic.( This information has been added in 18th/e of Harrison). Total surgical resection of benign meningiomas is curative. Tumors that cannot be resected ; may benefit from treatment with external beam radiotherapy or stereotactic surgery.