The 5th edition of the World Health Organization Classification of Haematolymphoid Tumours: Lymphoid Neoplasms

Abstract

We herein present an overview of the upcoming 5th edition of the World Health Organization Classification of Haematolymphoid Tumours focussing on lymphoid neoplasms. Myeloid and histiocytic neoplasms will be presented in a separate accompanying article. Besides listing the entities of the classification, we highlight and explain changes from the revised 4th edition. These include reorganization of entities by a hierarchical system as is adopted throughout the 5th edition of the WHO classification of tumours of all organ systems, modification of nomenclature for some entities, revision of diagnostic criteria or subtypes, deletion of certain entities, and introduction of new entities, as well as inclusion of tumour-like lesions, mesenchymal lesions specific to lymph node and spleen, and germline predisposition syndromes associated with the lymphoid neoplasms.

The 5th edition of the World Health Organization Classification of Haematolymphoid Tumours: Myeloid and Histiocytic/Dendritic Neoplasms

“…(2) moving follicular dendritic cell sarcoma and fibroblastic reticular cell tumor to a separate category; and, (3) addition of Rosai-Dorfman disease (RDD) and ALK-positive histiocytosis as disease types. Indeed, neoplasms that arise from lymphoid stromal cells such as follicular dendritic cell sarcoma and fibroblastic reticular cell tumor are now appropriately classified under the new chapter of "stroma-derived neoplasms of lymphoid tissues" as detailed in the companion manuscript [4].…”

“…3 Division of Hematology/Oncology, The Hospital for Sick Children, Toronto, ON, Canada. 4 The Steve and Cindy Rasmussen Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, OH, USA. 5 Pathology Unit, Department of Laboratories, Bambino Gesu Children's Hospital, IRCCS, Rome, Italy.…”

“…The last edition of the haematolymphoid classification dates back to 2008 and was revised in 2017. An overview of the lymphoid tumours is provided in a companion manuscript [4].…”

Classifying Germinal Center Derived Lymphomas—Navigate a Complex Transcriptional Landscape

“…DLBCL were further stratified into the cell of origin (COO) groups, germinal center B-cell like (GCB, 142 cases), activated B-cell-like (ABC, 133 cases), and unclassified (97 cases) DLBCL and DHL (58 cases) lymphomas. Cases have been classified according to the 4th Edition of the WHO classification, but Table 1 provides a translation into the 5th Edition [ 32 ].…”

The WHO Classification of Haematolymphoid Tumours

“…The outcome of this effort is another classification in the series that will help move the field forward by being based on a forwardlooking multidisciplinary effort grounded in genetic advances, with an eye on worldwide applicability. An overview of the classification and its salient features are provided in the two excellent companion manuscripts, which cover the classification of myeloid and histiocytic/dendritic neoplasms [12] and the classification of lymphoid neoplasms [13].…”