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International Consensus Classification of acute lymphoblastic leukemia/lymphoma

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The updated International Consensus Classification (ICC) of B-acute lymphoblastic leukemia (B-ALL) and T-acute lymphoblastic leukemia (T-ALL) includes both revisions to subtypes previously outlined in the 2016 WHO classification and several newly described entities. The ICC classification incorporates recent clinical, cytogenetic, and molecular data, with a particular emphasis on whole transcriptome analysis and gene expression (GEX) clustering studies. B-ALL classification is modified to further subclassify BCR::ABL1-positive B-ALL and hypodiploid B-ALL. Additionally, nine new categories of B-ALL are defined, including seven that contain distinguishing gene rearrangements, as well as two new categories that are characterized by a specific single gene mutation. Four provisional entities are also included in the updated B-ALL classification, although definitive identification of these subtypes requires GEX studies. T-ALL classification is also updated to incorporate BCL11B-activating rearrangements into early T-precursor (ETP) ALL taxonomy. Additionally, eight new provisional entities are added to the T-ALL subclassification. The clinical implications of the new entities are discussed, as are practical approaches to the use of different technologies in diagnosis. The enhanced specificity of the new classification will allow for improved risk stratification and optimized treatment plans for patients with ALL.

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Acute lymphoblastic leukemia


Adolescents and young adults


B-lymphoblastic leukemia




BCR::ABL1 B-ALL with lymphoid only involvement


BCR::ABL1-positive B-ALL with multilineage involvement




Chronic myeloid leukemia


Early T precursor


Fluorescence in situ hybridization


Gene expression


International Consensus Classification




Lymphoid blast phase

LMO1/2-r :

LMO1-rearranged or LMO2-rearranged


Mixed phenotype acute leukemia


Next generation sequencing


Not otherwise specified


PAX5-altered B-ALL


T-lymphoblastic leukemia


TAL1-rearranged or TAL2-rearranged


Tyrosine kinase inhibitors


Transcriptome sequencing


Whole genome sequencing (WGS)


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The authors thank the members of the working group including Elias Jabbour, Ching-Hon Pui, Kathryn Foucar, Nicola Goekbuget, Hartmut Doehner, and Mignon Loh, as well as Daniel Arber for thoughtful discussion. Additionally, the authors thank Dr. Qingsong Gao (St. Jude Children’s Research Hospital, Memphis, TN), who created Fig. 1.


A.S.D.: Financial support was received from P30 CA008748 (National Cancer Institute, National Institutes of Health).

C.G.M.: Financial support was received from P30 CA021765 and R35 CA197695 (National Cancer Institute, National Institutes of Health).

M.J.B.: Financial support was received from U10 CA180886 (National Cancer Institute, National Institutes of Health).

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M.J.B. was the initial contact for this invited review, and all authors (A.S.D., C.G.M., and M.J.B.) performed the literature search and data analysis, and drafted and/or critically revised the work. All authors have made substantial contributions to this review, have read and approved the final version submitted, and agree to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

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Correspondence to Michael J. Borowitz.

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The contents of Tables 1, 2, 3, and 4 are similar to those published in “Arber DA et al. [78]” because the current review expands on the International Consensus Classification first described in the June 2022 manuscript; however, the contents of the current manuscript have not been copyrighted.

Conflict of interest

Authors A.S.D. and M.J.B. declare no competing interests. Author C.G.M. has received speaker (Illumina and Amgen) and consultant (Faze, Beam) honoraria, and receives research funding from AbbVie and Pfizer.

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Duffield, A.S., Mullighan, C.G. & Borowitz, M.J. International Consensus Classification of acute lymphoblastic leukemia/lymphoma. Virchows Arch 482, 11–26 (2023).

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