Blood Journal
Leading the way in experimental and clinical research in hematology

The 2008 revision of the World Health Organization (WHO) classification of myeloid neoplasms and acute leukemia: rationale and important changes

  1. James W. Vardiman1,
  2. Jüergen Thiele2,
  3. Daniel A. Arber3,
  4. Richard D. Brunning4,
  5. Michael J. Borowitz5,
  6. Anna Porwit6,
  7. Nancy Lee Harris7,
  8. Michelle M. Le Beau8,
  9. Eva Hellström-Lindberg9,
  10. Ayalew Tefferi10, and
  11. Clara D. Bloomfield11
  1. 1Department of Pathology, University of Chicago, IL;
  2. 2Institute of Pathology, University of Cologne, Cologne, Germany;
  3. 3Department of Pathology, Stanford University Medical Center, CA;
  4. 4Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis;
  5. 5Department of Pathology and Oncology, Johns Hopkins Medical Institutions, Baltimore, MD;
  6. 6Department of Pathology, Karolinska University Hospital, Stockholm, Sweden;
  7. 7Department of Pathology, Massachusetts General Hospital and Harvard Medical School, Boston;
  8. 8Section of Hematology/Oncology, University of Chicago, IL;
  9. 9Department of Medicine, Karolinska University Hospital, Stockholm, Sweden;
  10. 10Division of Hematology, Mayo Clinic, Rochester, MN; and
  11. 11Comprehensive Cancer Center, The Ohio State University, Columbus


Recently the World Health Organization (WHO), in collaboration with the European Association for Haematopathology and the Society for Hematopathology, published a revised and updated edition of the WHO Classification of Tumors of the Hematopoietic and Lymphoid Tissues. The 4th edition of the WHO classification incorporates new information that has emerged from scientific and clinical studies in the interval since the publication of the 3rd edition in 2001, and includes new criteria for the recognition of some previously described neoplasms as well as clarification and refinement of the defining criteria for others. It also adds entities—some defined principally by genetic features—that have only recently been characterized. In this paper, the classification of myeloid neoplasms and acute leukemia is highlighted with the aim of familiarizing hematologists, clinical scientists, and hematopathologists not only with the major changes in the classification but also with the rationale for those changes.

  • Submitted March 5, 2009.
  • Accepted April 1, 2009.
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