HAEM4Backup:Acute Megakaryoblastic Leukemia (AMKL)

Primary Author(s)*

Cancer Category/Type

Cancer Sub-Classification / Subtype

Acute Megakaryoblastic Leukemia

Definition / Description of Disease

Acute megakaryoblastic leukemia is a myeloid disease defined by ≥20% blasts in the peripheral blood or bone marrow, of which ≥50% are of megakaryocyte lineage. In the 2016 revision to the World Health Organization (WHO) classification system, acute megakaryoblastic leukemia is a distinct entity within the section of Acute Myeloid Leukemia (AML), Not Otherwise Specified^[1]^[2]. 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).

AMKL in an individual with Down syndrome should be classified as a different entity, specifically Myeloid Leukemia Associated with Down Syndrome^[2].

AMKL associated with t(1;22)(p13.3;q13.1), or inv(3)(q21.3q26.2)/t(3;3)(q21.3;q26.2) should be classified as a different entity, specifically Acute Myeloid Leukemia (AML) with Recurrent Genetic Abnormalities: Acute Myeloid Leukemia (AML) Megakaryoblastic with t(1;22)(p13.3;q13.1);RBM15-MKL1 or Acute Myeloid Leukemia (AML) with inv(3)(q21.3q26.2) or t(3;3)(q21.3;q26.2);GATA2, MECOM^[2].

Synonyms / Terminology

French-American-British (FAB) classification M7^[2].

Epidemiology / Prevalence

AMKL comprises between 4% and 15% of newly diagnosed pediatric acute myeloid leukemia patients^[3].

Clinical Features

Common manifestations include cytopenias (often thrombocytopenia)^[2].
An association between acute megakaryoblastic leukemia and mediastrinal germ cell tumors has been described^[4].

Sites of Involvement

Bone marrow.

Morphologic Features

Megakaryoblasts are usually medium-sized to large cells with basophilic cytoplasm and a high nuclear-cytoplasmic ratio.
Nuclei are round, slightly irregular or indented with finely reticular chromatin and 1 - 3 nucleoli.
Bone marrow myelofibrosis is common.

Immunophenotype

Cytochemistry

Megakaryoblasts are typically negative for myeloperoxidase (MPO) and stain negatively with Sudan black B.
Variable reactivity to periodic acid-Schiff (PAS) staining from negative to focal or strongly positive.

Immunophenotype including:

One or more of the platelet glycoproteins: CD41, CD61, and CD42b
Myeloid-associated markers may be positive: CD13, CD33
CD34, CD45, and HLA-DR are often negative, especially in children

Finding	Marker
Positive (universal)	EXAMPLE CD1
Positive (subset)	EXAMPLE CD2
Negative (universal)	EXAMPLE CD3
Negative (subset)	EXAMPLE CD4

Chromosomal Rearrangements (Gene Fusions)

None.

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

No unique chromosomal abnormality is associated with AMKL.

Isochromosome 12p is often observed in young males with mediatinal germ tumors and AMKL^[5].

Genomic Gain/Loss/LOH

None

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)

None.

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)

None.

Genes and Main Pathways Involved

None.

Diagnostic Testing Methods

Conventional chromosome analysis

FISH myeloid panel

Clinical Significance (Diagnosis, Prognosis and Therapeutic Implications)

Diagnosis

The main differential diagnoses of acute megakaryoblastic leukemia include: AML with minimal differentiation, AML-MRC, acute panmeylosis with myelofibrosis, lymphoblastic leukemia, pure erythroid leukemia, blastic transformation of chronic myeloid leukemia, and the blast phase of any other myeloproliferative neoplasm^[2].

Prognosis

The prognosis of AMKL is usually poorer than that of other AML types, Acute Myeloid Leukemia (AML) Megakaryoblastic with t(1;22)(p13.3;q13.1);RBM15-MKL1, and Myeloid Leukemia Associated with Down Syndrome^[2]^[6].

Familial Forms

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Other Information

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Links

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References

↑ 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. World Health Organization Classification of Tumours of Haematopoietic and Lymphoid Tissues, Revised 4th edition. IARC Press: Lyon, France, p162-164.
↑ ^2.0 ^2.1 ^2.2 ^2.3 ^2.4 ^2.5 ^2.6 Arber, Daniel A.; et al. (2016). "The 2016 revision to the World Health Organization classification of myeloid neoplasms and acute leukemia". Blood. 127 (20): 2391–2405. doi:10.1182/blood-2016-03-643544. ISSN 1528-0020. PMID 27069254.
↑ Gruber, Tanja A.; et al. (2015). "The biology of pediatric acute megakaryoblastic leukemia". Blood. 126 (8): 943–949. doi:10.1182/blood-2015-05-567859. ISSN 1528-0020. PMC 4551356. PMID 26186939.
↑ Nichols, C. R.; et al. (1990). "Hematologic neoplasia associated with primary mediastinal germ-cell tumors". The New England Journal of Medicine. 322 (20): 1425–1429. doi:10.1056/NEJM199005173222004. ISSN 0028-4793. PMID 2158625.
↑ Orazi, A.; et al. (1993). "Hematopoietic precursor cells within the yolk sac tumor component are the source of secondary hematopoietic malignancies in patients with mediastinal germ cell tumors". Cancer. 71 (12): 3873–3881. doi:10.1002/1097-0142(19930615)71:123.0.co;2-1. ISSN 0008-543X. PMID 8389653.
↑ Oki, Yasuhiro; et al. (2006). "Adult acute megakaryocytic leukemia: an analysis of 37 patients treated at M.D. Anderson Cancer Center". Blood. 107 (3): 880–884. doi:10.1182/blood-2005-06-2450. ISSN 0006-4971. PMID 16123215.

Notes

*Primary authors will typically be those that initially create and complete the content of a page. If a subsequent user modifies the content and feels the effort put forth is of high enough significance to warrant listing in the authorship section, please contact the CCGA coordinators (contact information provided on the homepage). Additional global feedback or concerns are also welcome.

[1] 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. World Health Organization Classification of Tumours of Haematopoietic and Lymphoid Tissues, Revised 4th edition. IARC Press: Lyon, France, p162-164.

[:0-2] 2.0 ^2.1 ^2.2 ^2.3 ^2.4 ^2.5 ^2.6 Arber, Daniel A.; et al. (2016). "The 2016 revision to the World Health Organization classification of myeloid neoplasms and acute leukemia". Blood. 127 (20): 2391–2405. doi:10.1182/blood-2016-03-643544. ISSN 1528-0020. PMID 27069254.

[3] Gruber, Tanja A.; et al. (2015). "The biology of pediatric acute megakaryoblastic leukemia". Blood. 126 (8): 943–949. doi:10.1182/blood-2015-05-567859. ISSN 1528-0020. PMC 4551356. PMID 26186939.

[4] Nichols, C. R.; et al. (1990). "Hematologic neoplasia associated with primary mediastinal germ-cell tumors". The New England Journal of Medicine. 322 (20): 1425–1429. doi:10.1056/NEJM199005173222004. ISSN 0028-4793. PMID 2158625.

[5] Orazi, A.; et al. (1993). "Hematopoietic precursor cells within the yolk sac tumor component are the source of secondary hematopoietic malignancies in patients with mediastinal germ cell tumors". Cancer. 71 (12): 3873–3881. doi:10.1002/1097-0142(19930615)71:123.0.co;2-1. ISSN 0008-543X. PMID 8389653.

[6] Oki, Yasuhiro; et al. (2006). "Adult acute megakaryocytic leukemia: an analysis of 37 patients treated at M.D. Anderson Cancer Center". Blood. 107 (3): 880–884. doi:10.1182/blood-2005-06-2450. ISSN 0006-4971. PMID 16123215.

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