Controversies in the recent (2016) World Health Organization classification of acute myeloid leukemia

The current World Health Organization (WHO) Classification of acute myeloid leukemia (AML), developed in 2016 and published in 2017, codifies the defining features of AML and recognizes several subtypes based on clinical, morphologic, and genetic features. This classification is widely used for the purposes of assigning patients to specific therapeutic approaches and entry into clinical trials. Although the WHO Classification ultimately has its origins in the original 1976 French-American-British Classification, it has been periodically updated by the incorporation of a large body of evidence and input from both diagnosticians and clinicians who study and treat AML. Nevertheless, the recent accumulation of genetic data on the molecular underpinnings of myeloid neoplasms as well as numerous recently approved novel therapies have highlighted areas of controversy in how we currently define and classify AML; the 2016 WHO Classification will continually be revised and updated in future versions based on these advances. The purpose of this review is to explore areas of potential refinement in the current WHO Classification of AML, both in terms of its criteria defining the disease as well as the specific disease subtypes.