Review ArticlesThe 2020 WHO Classification of Tumors of Bone: An Updated ReviewChoi, Joon Hyuk MD, PhD*; Ro, Jae Y. MD, PhD†Author Information *Department of Pathology, Yeungnam University College of Medicine, Daegu, South Korea †Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Weill Medical College of Cornell University, Houston, TX The authors have no funding or conflicts of interest to disclose. Reprints: Joon Hyuk Choi, MD, PhD, Department of Pathology, Yeungnam University College of Medicine, 170 Hyeonchung-ro, Namgu, Daegu 42415, South Korea (e-mail: [email protected]). All figures can be viewed online in color at www.anatomicpathology.com. Advances In Anatomic Pathology: May 2021 - Volume 28 - Issue 3 - p 119-138 doi: 10.1097/PAP.0000000000000293 Buy Metrics Abstract Bone tumors are a rare and heterogeneous group of neoplasms that occur in the bone. The diversity and considerable morphologic overlap of bone tumors with other mesenchymal and nonmesenchymal bone lesions can complicate diagnosis. Accurate histologic diagnosis is crucial for appropriate management and prognostication. Since the publication of the fourth edition of the World Health Organization (WHO) classification of tumors of soft tissue and bone in 2013, significant advances have been made in our understanding of bone tumor molecular biology, classification, prognostication, and treatment. Detection of tumor-specific molecular alterations can facilitate the accurate diagnosis of histologically challenging cases. The fifth edition of the 2020 WHO classification of tumors of soft tissue and bone tumors provides an updated classification scheme and essential diagnostic criteria for bone tumors. Herein, we summarize these updates, focusing on major changes in each category of bone tumor, the newly described tumor entities and subtypes of existing tumor types, and newly described molecular and genetic data. Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.