Abstract. As its historical name glioblastoma multiforme implies, glioblastoma is a histologically diverse, World Health Organization grade IV astrocytic neoplasm. In spite of its simple definition of presence of vascular proliferation and/or necrosis in a diffuse astrocytoma, the wide variety of cytohistomorphologic appearances overlap with many other neoplastic or non-neoplastic lesions. Here, after a brief … More If it is Not a Glioblastoma, Then What is it? A Differential Diagnostic Review.