The gross features of this dural-based tumor are consistent with meningioma, the most frequent benign intracranial neoplasm. It arises from meningothelial cells and histologically consists of whorls of elongated cells with scattered psammoma bodies. The benign behavior of this tumor is apparent from its "pushing" pattern of growth. The tumor tends to expand downward, compressing the brain, but without invading it. For this reason, this tumor can be easily removed at surgery. An aeriovenous malformation is a vascular aggregate of aeries, veins, and vessels with intermediate characteristics. These lesions are usually intracerebral and manifest with hemorrhage or seizures. Glioblastoma multiforme is the most frequent malignant intracerebral tumor. It arises from neoplastic transformation of astrocytes within the white matter. Grossly, it is characterized by a variegated appearance, with areas of solid tumor alternating with necrosis and hemorrhage. Medulloblastoma develops from the cerebellar vermis, usually in children. It is composed of small, primitive-appearing neoplastic cells.