Introduction to the Fifth Edition of the World Health Organization Classification of Tumors of Hematopoietic and Lymphoid Tissues

The World Health Organization (WHO) Classification of Tumors of Hematopoietic and Lymphoid Tissues has been the internationally accepted standard for over 20 years. The fifth edition of the WHO Classification (WHO-HEM5) is a multidisciplinary effort by pathologists, clinicians and other specialists that builds upon the revised fourth edition published in 2017. Entities in WHO-HEM5 are organized hierarchically. There are several changes in WHO-HEM5 from the previous edition, including addition of new entities, deletion of some entities and recognition or revision of some subtypes reflecting scientific developments and clinical advances during the past few years. Essential and desirable criteria for each entity are included. Here we introduce WHO-HEM5. Four reviews will follow that emphasize important aspects of the classification. (c) 2023 United States & Canadian Academy of Pathology. Published by Elsevier Inc. All rights reserved.

Automated summary

The World Health Organization's classification of tumors of hematopoietic and lymphoid tissues has been the globally accepted standard for over 20 years. The fifth edition, a collaborative effort by pathologists, clinicians, and other specialists, builds upon the previous edition published in 2017. There are several changes in the new edition, including the addition, deletion, and revision of entities to reflect scientific and clinical advancements. Essential and desirable criteria are provided for each entity.