Acute Myeloid Leukemia (AML) with Maturation
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Primary Author(s)*
Jennelle C. Hodge, PhD, FACMG
Cancer Category/Type
Cancer Sub-Classification / Subtype
Acute myeloid leukemia (AML) with maturation
Definition / Description of Disease
This is a distinct entity in the World Health Organization (WHO) classification system within the section of HAEM4: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 M2[1].
Epidemiology / Prevalence
Accounts for 10% of AML, occurring in all ages including 20% in young patients (<25 years old) and 40% in older patients (≥60 years old)[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[1].
Sites of Involvement
Bone marrow, Blood
Morphologic Features
This AML subtype is characterized by the presence of ≥20% blasts in the bone marrow or blood combined with evidence of maturation in the bone marrow; specifically, ≥10% maturing cells of granulocytic lineage and <20% cells of monocyte lineage[1]. The blasts may or may not have azurophilic granulation but Auer rods and hypercullularity are typically observed. Bone marrow cell constitution includes ≥10% promyelocytes, myelocytes and mature nuetrophils, as well as elevated eosinophil precursors which lack the cytological or cytochemical abnormalities characteristic of the abnormal eosinophils in HAEM5:Acute myeloid leukaemia with CBFB::MYH11 fusion. Basophils and mast calls are sometimes increased, and variable dysplasia occurs but ≤50% of cells in two lineages show dysplasia.
Immunophenotype
The characteristic immunophenotype associated with this entity is listed in the table below. The blasts express one or more of the myeloid-associated antigens, in some cases have a pattern associated with granulocytic differentiation, and typically lack monocytic markers[1].
| Finding | Marker |
|---|---|
| Positive (universal) | Myeloid-associated antigens (CD13, CD33, CD65, CD11b, and/or CD15) |
| Positive (subset) | KIT(CD117), CD34 and HLA-DR may be present in some blasts |
| Negative (universal) | Monocytic markers (CD14, CD36, CD64) |
| Negative (subset) | CD7 (20-30%), CD56, CD2, CD19 and CD4 are uncommon (~10%; may be found only in immature blasts) |
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) |
|---|---|---|---|---|
| EXAMPLE TP53 | EXAMPLE R273H | EXAMPLE Tumor Suppressor | EXAMPLE LOF | EXAMPLE 20% |
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
Unknown
Diagnostic Testing Methods
Histology and immunophenotype
Clinical Significance (Diagnosis, Prognosis and Therapeutic Implications)
The differential diagnosis includes 1) MDS with excess blasts in cases with a low blast percentage, 2) AML without Maturation in cases with a high blast percentage, and 3) HAEM5:Acute myelomonocytic leukaemia in cases with increased monocytes. Of note, Acute Myeloid Leukemia (AML) with t(8;21)(q22;q22.1);RUNX1-RUNX1T1 typically has overlapping histologic features as AML with Maturation, but the former should be classified according to its genetic abnormality (i.e. as a subcategory of the entity HAEM4:Acute Myeloid Leukemia (AML) with Recurrent Genetic Abnormalities).
Familial Forms
No familial forms currently known.
Other Information
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Links
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References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 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, p158-159.
Notes
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