RT Journal Article SR Electronic T1 The 2021 World Health Organization Classification of Tumors of the Central Nervous System: What Neuroradiologists Need to Know JF American Journal of Neuroradiology JO Am. J. Neuroradiol. FD American Society of Neuroradiology SP 928 OP 937 DO 10.3174/ajnr.A7462 VO 43 IS 7 A1 A.G. Osborn A1 D.N. Louis A1 T.Y. Poussaint A1 L.L. Linscott A1 K.L. Salzman YR 2022 UL http://www.ajnr.org/content/43/7/928.abstract AB SUMMARY: Neuroradiologists play a key role in brain tumor diagnosis and management. Staying current with the latest classification systems and diagnostic markers is important to provide optimal patient care. Publication of the 2016 World Health Organization Classification of Tumors of the Central Nervous System introduced a paradigm shift in the diagnosis of CNS neoplasms. For the first time, both histologic features and genetic alterations were incorporated into the diagnostic framework, classifying and grading brain tumors. The newly published 2021 World Health Organization Classification of Tumors of the Central Nervous System, May 2021, 5th edition, has added even more molecular features and updated pathologic diagnoses. We present, summarize, and illustrate the most salient aspects of the new 5th edition. We have selected the key “must know” topics for practicing neuroradiologists.DGONCdiffuse glioneuronal tumor with oligodendroglioma-like features and nuclear clustersEPNependymomaETMRembryonal tumor with multilayered rosettesFISHfluorescence in situ hybridizationNECnot elsewhere classified; NOS = not otherwise specifiedMBmedulloblastomaMGNTmyxoid glioneuronal tumorMVNTmultinodular and vacuolating neuronal tumorPFposterior fossaSCspinal cordSTsupratentorialWHOWorld Health OrganizationIDHisocitrate dehydrogenase