What are menigioma?

➢ Usually meningiomas, beneath the dura, compresse the underlying cerebral hemisphere. ➢Most often benign ➢ Represent 20% of primary barin tumors ➢Peak frequency around 5th decade ➢These neoplasms arise from meningothelial arachnoid cap cells ➢ They are typically well-circumscribed masses that are amenable to resection. ➢Sometimes they produce a flattened mass, and sometimes the overlying bone shows hyperostosis. ➢Rarely, meningiomas can be more atypical and recur, or aggressive (anaplastic) and invade the underlying brain Predisposing factos (genetics and ionizing radiation) ➢WHO distinguishes three prognostic grades of meningiomas, with several histological variants for each grade: ● grade I meningioma (benign) ● atypical meningioma (grade II) ● malignant meningioma (grade III)T