Glioblastoma

The most malignant astrocytic tumor (WHO grade 4). It is composed of poorly differentiated neoplastic astrocytes and is characterized by the presence of cellular polymorphism, nuclear atypia, brisk mitotic activity, vascular thrombosis, microvascular proliferation, and necrosis. It typically affects adults and is preferentially located in the cerebral hemispheres. (Adapted from WHO)

Source: NCI Thesaurus (C3058).