Contemporary approach to diagnosis and classification of acute myeloid leukemia

The term acute myeloid leukemia (AML) refers to a group of myeloid neoplasms characterized by maturation arrest, classically defined as ≥20% myeloblasts or myeloblast equivalents in the peripheral blood or bone marrow. In recent decades, a wealth of genetic information has reshaped our understanding of AML biology and enabled recognition of discrete molecular subgroups. However, questions remain, especially regarding which genetic lesions are class-defining and which are, at most, prognostic. These questions acquired particular salience with the advent of two classification systems, the 2022 International Consensus Classification and the WHO 5th Edition (WHO), replacing the prior WHO revised 4th Edition. While efforts are underway to unite current classification schemes, it is essential for pathologists to understand the rationale behind AML classification in the interest of patient care. Given the growing complexity in this area, this review aims to provide a practical guide for AML diagnosis and contemporary classification while highlighting areas of active inquiry which may inform future classification.