The 2016 revision to the World Health Organization classification of myeloid neoplasms and acute leukemia

Daniel A. Arber, Attilio Orazi, Robert Hasserjian, Jürgen Thiele, Michael J. Borowitz, Michelle M. Le Beau, Clara D. Bloomfield, Mario Cazzola and James W. Vardiman
This article has an Erratum 128(3):462

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  • RE: The 2016 revision to the WHO classification of myeloid neoplasms and acute leukemia

    The article by Arber, D et al on updated WHO classification of myeloid neoplasms is very timely because it incorporates significant progress made over the past 8 years.


    Although not specifically mentioned in this publication, I would appreciate clarification in relation to the WHO classification of the acute myeloid leukemia (AML), NOS particularly in this era when cytochemistry is being phased out in many laboratories & being substituted by immunophenotyping. This applies particularly to the following subgroups:

    1. Acute myeloid leukemia with minimal differentiation (M0) versus acute myeloid leukemia without maturation (M1)

    2. AML with maturation (M2) versus acute myelomocytic leukemia (AMML) as well as

    3. AMML (M4) versus acute monocytic leukaemia (M5).


    It is stated in the WHO 2008 publication that M0 is an AML with no evidence of myeloid differentiation by morphology & light microscopy cytochemistry. The myeloid nature of blasts is demonstrated by immunological markers and/or ultrastructural studies including ultrastructural cytochemistry. Under the subheading of immunophenotype it is stated that MPO is negative by cytochemistry but may be positive in a fraction of blasts by flow cytometry or immunohistochemistry. Under the category of M1, it states that the myeloid nature of blasts is demonstrated by MPO or SBB (>3% or more of blasts) positivity and/or Auer rods.



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    Conflict of Interest:
    None declared.
  • The 2016 WHO criteria for the diagnosis of Polycythemia Vera: benefits and potential risks.
    • Vincent Ethier, Hematologist Department of Laboratory Hematology Hôpital Maisonneuve-Rosemont, Université de Montréal, Montréal, QC, Canada
    • Other Contributors:
      • Shireen Sirhan, Hematologist
      • Harold J. Olney, Hematologist
      • Vikas Gupta, Hematologist
      • Lambert Busque, Hematologist

    Polycythemia vera (PV) was until recently diagnosed according to the 2008 World Health Organization (WHO) classification using JAK2 mutation and hemoglobin (Hb) values > 185 g/L and > 165 g/L in males and females, respectively, as major criteria1. In its 2016 revision, the WHO lowers these thresholds to 165 g/L for men or 160 g/L for women2. This change takes into account recent studies showing that a significant proportion of JAK2 V617F-positive PV patients present with Hb values lower than these thresholds3-6. This presentation has become known as masked PV (mPV) and seems to be associated with a similar clinical course as other PV patients, with an even higher risk of thrombotic events3,4. In addition, the new criteria promote bone marrow biopsy as a mandatory criterion for diagnosis in an attempt to confirm mPV cases and detect occasional increases in reticulin fibers, which have been associated with a worse outcome2,7. Recognition of mPV cases represents an important advancement in the field and will likely lead to avoidance of potentially dramatic thrombotic events by providing an earlier diagnosis. Ultimately, the objective is also to avoid misdiagnosing mPV for ET since a diagnosis of ET means that phlebotomies will erroneously not be considered in young patients who could derive clinical benefit from this simple therapeutic intervention.

    Since the WHO criteria are appropriately considered as a diagnostic standard, use of the recently published new ve...

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    Conflict of Interest:
    Conflict-of-interest disclosure:
    Vincent Ethier: no relevant conflict of interests.
    Shireen Sirhan: Received honorarium from Novartis and served on advisory board panel for Novartis.
    Harold J. Olney: Received honorarium from Novartis and served on advisory board panel for Novartis.
    Vikas Gupta: Received research funding from Incyte and Novartis, received honorarium from Novartis/Incyte, and served on advisory board panel for Novartis.
    Lambert Busque: Received honorarium from Novartis and served on advisory