Pathology and classification of tumors of the nervous system

Abstract

Rudolph Virchow (1821-1902), the founder of cellular pathology, already separated the gliomas from the 'psammomas', the 'melanomas' and other 'sarcomas' of the nervous system in 1864/65 (Virchow 1864/65). However, it was not before 1926 that Bailey and Cushing developed the first systematic classification scheme for gliomas and introduced the concept of brain tumor grading (Bailey and Cushing 1926). The first World Health Organization (WHO) classification of tumors of the nervous system was published in 1979 (Zülch 1979), followed by revisions in 1993 (Kleihues et al. 1993) and 2000 (Kleihues and Cavenee 2000). All WHO classifications, including the latest version of 2000 (Table 1), followed the his-togenetic principle originally proposed by Bailey and Cushing (1926). Based on morphologic and immu-nohistochemical features, each tumor entity is classified according to its presumed cell of origin. Although commonly used, this concept is challenged by the fact that the actual cell of origin is unknown for most brain tumors. Furthermore, experimental evidence from mouse models suggests that gliomas, for example, are more likely to arise from glial precursor cells than from terminally differentiated astrocytes or oligodendrocytes (Shih and Holland 2004). Nevertheless, histologic classification according to the WHO criteria allows for a meaningful separation of biologically and clinically distinct brain tumor entities that is unsurpassed by any other diagnostic approach so far. Thus, the morphologic classification of brain tumors is and will remain the diagnostic 'gold standard' in neuro-oncology. © Springer-Verlag Berlin Heidelberg 2006.