Classification of acute myeloid leukemia
The classification system for acute myeloid leukemia (AML) was developed by the World Health Organization (WHO). An older system called FAB classification (based mainly on how the leukemia cells look under a microscope) is no longer in use.
WHO classification system
The WHO system uses cell characteristics and genetics to classify AML into several groups.
AML with certain genetic abnormalities
Some types of AML have specific gene or chromosome changes:
AML with a translocation between chromosomes 8 and 21, RUNX1-RUNX1T1
- AML with a translocation or inversion in chromosome 16, CBFB-MYH11
- APL with the PML-RARA fusion gene (translocation between the PML region in chromosome 15 and the RARA gene region in chromosome 17)
- AML with a translocation between chromosomes 9 and 11, MLLT3-KMT2A
- AML with a translocation or inversion in chromosome 3, GATA2, MECOM
- AML (megakaryoblastic) with a translocation between chromosomes 1 and 22, RBM15-MKL1
- AML with the BCR-ABL1 (BCR-ABL) fusion gene
- AML with mutated NPM1 gene
- AML with biallelic mutations of the CEBPA gene (mutations in both copies of the CEBPA gene)
- AML with mutated RUNX1 gene
AML with myelodysplasia-related changes
Some types of AML can develop after myelodysplastic syndromes or myelodysplastic/myeloproliferative neoplasms.
AML related to previous chemotherapy or radiation
This type of AML is related to previously having had chemotherapy with an alkylating drug or radiation therapy.
AML, not otherwise specified
This is used for AML that does not fall into one of the other categories. This classification is based on how the leukemia cells look under a microscope and includes:
AML with minimal differentiation
AML without maturation
AML with maturation
acute myelomonocytic leukemia (AMML)
acute monocytic leukemia
pure erythroid leukemia
acute megakaryoblastic leukemia
acute basophilic leukemia
acute panmyelosis with myelofibrosis
Myeloid sarcoma
Myeloid sarcoma is a tumour that occurs outside of the bone marrow.
Myeloid proliferations related to Down syndrome
This is AML related to Down syndrome.
Undifferentiated and biphenotypic acute leukemias
These leukemias have both lymphoblastic and myeloid features. They are very rare. They are sometimes called mixed phenotype acute leukemias.