Commentary on the WHO Classification of Tumors of the Nervous System

Abstract

This article provides a sobering view of the changes introduced in the WHO classification of nervous system tumors published in 2000. The authors have drawn particular attention to the new tumor entities and histological variants included in the new Blue Book series and emphasize the importance of cytogenetic and molecular biologic data in the understanding of these tumors. Since the new WHO Blue Book has already benefited from wide distribution, it might have been of greater interest for the reader to learn more about a) the strategies used by the working group to reach consensus, b) the debates behind the choice of histological characterization and operational definition of different tumor categories, and c) more general conceptual analyses regarding the role and limitations of the WHO classification and its potential impact on the medical and scientific community. To begin with, it should be emphasized that the “new” WHO Blue Book is in itself a revised version of the book edited one year earlier by Kleihues and Cavenee. The working methods chosen by the editors are essentially unchanged. These comprised three steps: a consensus manuscript for each chapter was initially written by a limited number of selected authors; …