Acute Myeloid Leukemia (AML) without Maturation

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Primary Author(s)*

Jennelle C. Hodge, PhD, FACMG

Cancer Category/Type

Acute Myeloid Leukemia

Cancer Sub-Classification / Subtype

Acute myeloid leukemia (AML) without maturation

Definition / Description of Disease

This is a distinct entity in the World Health Organization (WHO) classification system within the section of Acute Myeloid Leukemia (AML), Not Otherwise Specified[1]. This entity does not meet the criteria for inclusion in any of the other AML groups (i.e. AML with Recurrent Genetic Abnormalities, AML with Myelodysplasia-Related Changes, or Therapy-Related Myeloid Neoplasms). There is currently no known recurrent chromosomal abnormality associated with this entity[1].

Synonyms / Terminology

American-British (FAB) classification M1 [1].

Epidemiology / Prevalence

Accounts for 5-10% of AML, occurring mostly in adults (median age of ~46 years)[1].

Clinical Features

Usually presents with symptoms of bone marrow failure, including anemia, thrombocytopenia and neutropenia. There is also variability in the white blood cell and blast counts, which can include leukocytosis with markedly increased blasts[1].

Sites of Involvement

Bone marrow

Morphologic Features

This AML subtype is characterized by the presence in the bone marrow of a high percentage of myeloid blasts without significant evidence of maturation; specifically, <10% of the nucleated bone marrow cells represent maturing cells of the granulocytic lineage[1]. Cases are typically markedly hypercellular (range also includes normocellular and hypocellular) and can involve myeloblasts with azurophilic granules and/or Auer rods, while other cases present with cells resembling lymphoblasts that lack azurophilic granules[1].


The characteristic immunophenotype associated with this entity is listed in the table below. The myeloid nature of the blasts includes an immunophenotype positive for MPO or SBB in ≥3% of the blasts and/or the presence of Auer rods, as well as typically positivity for one or more myeloid-associated antigens[1].

Finding Marker
Positive (universal) Myeloperoxidase (MPO), Sudan Black B (SBB), one or more of CD13, CD33 and/or KIT(CD117)
Positive (subset) CD34 and HLA-DR (only 70%), CD11b
Negative (universal) Granulocytic maturation markers (CD15, CD65), Monocytic markers (CD14, CD64), B-cell and T-cell cytoplasmic lymphoid markers (cCD3, cCD79a, cCD22)
Negative (subset) CD7 (only 30%), Lymphoid-associated membrane markers (CD2, CD4, CD19, CD56; only 10-20%)

Chromosomal Rearrangements (Gene Fusions)

There is currently no known recurrent chromosomal abnormality associated with this entity.

Chromosomal Rearrangement Genes in Fusion (5’ or 3’ Segments) Pathogenic Derivative Prevalence
EXAMPLE t(9;22)(q34;q11.2) EXAMPLE 3'ABL1 / 5'BCR EXAMPLE der(22) EXAMPLE 5%
EXAMPLE t(8;21)(q22;q22) EXAMPLE 5'RUNX1 / 3'RUNXT1 EXAMPLE der(8) EXAMPLE 5%

Characteristic Chromosomal Aberrations / Patterns

There is currently no known recurrent chromosomal abnormality associated with this entity.

Genomic Gain/Loss/LOH

There is currently no known recurrent chromosomal abnormality associated with this entity.

Chromosome Number Gain/Loss/Amp/LOH Region
EXAMPLE 8 EXAMPLE Gain EXAMPLE chr8:0-1000000
EXAMPLE 7 EXAMPLE Loss EXAMPLE chr7:0-1000000

Gene Mutations (SNV/INDEL)

Currently there is currently no known recurrent gene mutations associated with this entity.

Gene Mutation Oncogene/Tumor Suppressor/Other Presumed Mechanism (LOF/GOF/Other; Driver/Passenger) Prevalence (COSMIC/TCGA/Other)

Other Mutations

Type Gene/Region/Other
Concomitant Mutations EXAMPLE IDH1 R123H
Secondary Mutations EXAMPLE Trisomy 7
Mutually Exclusive EXAMPLE EGFR Amplification

Epigenomics (Methylation)

Not applicable

Genes and Main Pathways Involved


Diagnostic Testing Methods

Histology and immunophenotype

Clinical Significance (Diagnosis, Prognosis and Therapeutic Implications)

The differential diagnosis includes 1) Lymphoblastic Leukemia in the presence of blast cells lacking granules or in cases with a low percentage of MPO-positive blasts and 2) AML with Maturation in cases with a higher percentage of MPO-positive blasts[1].

Familial Forms

No familial forms currently known.

Other Information

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  1. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 Arber DA, et al., (2017). Acute myeloid leukaemia with recurrent genetic abnormalities, in World Health Organization Classification of Tumours of Haematopoietic and Lymphoid Tissues, Revised 4th edition. Swerdlow SH, Campo E, Harris NL, Jaffe ES, Pileri SA, Stein H, Thiele J, Arber DA, Hasserjian RP, Le Beau MM, Orazi A, and Siebert R, Editors. IARC Press: Lyon, France, p157-158.


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