meningioma /minin′jē·ō″mə/ [Gk, meninx, membrane, oma, tumor] , a mesenchymal fibroblastic tumor of the membranes enveloping the brain and spinal cord. Meningiomas grow slowly, are usually vascular, and occur most commonly near the superior longitudinal transverse and cavernous sinuses of the dura mater of the brain. The tumors may be nodular, plaquelike, or diffuse lesions that invade the skull, causing bone erosion and compression of brain tissue. Meningiomas usually occur in adults.
