The 2021 WHO Classification of Tumors of the Central Nervous System: a summary

Abstract

Abstract The fifth edition of the WHO Classification of Tumors of the Central Nervous System (CNS), published in 2021, is the sixth version of the international standard for the classification of brain and spinal cord tumors. Building on the 2016 updated fourth edition and the work of the Consortium to Inform Molecular and Practical Approaches to CNS Tumor Taxonomy, the 2021 fifth edition introduces major changes that advance the role of molecular diagnostics in CNS tumor classification. At the same time, it remains wedded to other established approaches to tumor diagnosis such as histology and immunohistochemistry. In doing so, the fifth edition establishes some different approaches to both CNS tumor nomenclature and grading and it emphasizes the importance of integrated diagnoses and layered reports. New tumor types and subtypes are introduced, some based on novel diagnostic technologies such as DNA methylome profiling. The present review summarizes the major general changes in the 2021 fifth edition classification and the specific changes in each taxonomic category. It is hoped that this summary provides an overview to facilitate more in-depth exploration of the entire fifth edition of the WHO Classification of Tumors of the Central Nervous System.

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Affiliated Institutions

• Massachusetts General Hospital US
• Centre National de la Recherche Scientifique FR
• Heinrich Heine University Düsseldorf DE
• German Cancer Research Center DE
• Harvard University US
• Northwestern University US
• Deutschen Konsortium für Translationale Krebsforschung
• University Hospital Heidelberg DE
• Düsseldorf University Hospital DE
• Princess Máxima Center NL
• Centre international de recherche sur le cancer FR
• Aix-Marseille Université FR
• University of Toronto CA
• Amsterdam University Medical Centers NL
• Chinese University of Hong Kong HK
• National Center for Tumor Diseases DE
• Hôpital de la Timone FR
• SickKids Foundation CA
• University of Turin IT
• St. Jude Children's Research Hospital US
• University of California, San Francisco US
• Institut de Neurophysiopathologie FR
• Heidelberg University DE
• Hospital for Sick Children CA

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