HISTOPATHOLOGIC CLASSIFICATION - Primary brain tumors are classified by light microscopy according to their predominant cell type and graded based upon the presence or absence of standard pathologic features. Historical attempts at developing a classification system for brain tumors date back to the 1830s. The German pathologist Rudolf Virchow first introduced the term "glioma" in 1860. Virchow was also the first to attempt a correlation of microscopic to macroscopic features of CNS tumors.
CELLULAR CLASSIFICATION - The classification of brain tumors is based on both histopathological characteristics and location in the brain. Undifferentiated neuroectodermal tumors of the cerebellum have historically been referred to as medulloblastomas, while tumors of identical histology in the pineal region would be diagnosed as pineoblastomas. The nomenclature of pediatric brain tumors is controversial and potentially confusing. Some pathologists advocate abandoning the traditional morphologically-based classifications such as medulloblastoma in favor of a terminology that relies more extensively on the phenotypic characteristics of the tumor.
