Meningiomas are the most common primary tumor of the central nervous system, arising from the arachnoid "cap" cells of the arachnoid villi in the meninges. These tumors are usually benign in nature; however, they can be malignant. Causes Most cases are sporadic while some are familial. Persons who've undergone radiation to the scalp are more at risk for developing meningiomas. The most frequent genetic mutations involved in meningiomas are inactivation mutations in the neurofibromatosis 2 gene… (More on Meningioma)