Acute Myeloid Leukemia



  • Acute myeloid leukemia (AML) results from a block in differentiation and unregulated proliferation of myeloid progenitor cells.
  • AML is classified according to the World Health Organization (WHO) classification (2008).
  • Formerly classified by French-American-British (FAB) classification
  • WHO classification is based on genetic alterations, whereas FAB is based on morphology.


  • AML is the seventh most common pediatric malignancy.
  • Leukemia that occurs in first 4 weeks of life is usually AML.
  • Ratio of AML to acute lymphoblastic leukemia (ALL) throughout childhood is 1:5.
  • Boys and girls are equally affected.
  • Rates are highest in Asian and Pacific Islanders followed by Hispanics, Caucasians, and African Americans.
  • AML incidence peaks in infants <1 year of age and again in children 10 to 14 years of age.
  • Around 500 children per year in the United States

Risk Factors


  • 20–30% of pediatric blast cells have normal karyotype versus 40–50% in adults.
  • 60% of abnormal karyotypes fall into known subgroups.
  • Translocations or duplications of the MLL gene at 11q23 or monosomy 7 carry a poor prognosis.
  • These genetic abnormalities are found in many cases of therapy-induced AML.
  • FLT3-ITD with high allelic ratio, a drug targetable lesion, has also been shown to carry a poor prognosis.
  • Translocations t(8;21), t(15;17), and inv(16), as well as NPM and CEPBα mutations carry a good prognosis.
  • AML associated with Down syndrome has an excellent prognosis.
  • Certain congenital syndromes that carry an increased risk of AML:
    • Fanconi anemia
    • Bloom syndrome
    • Neurofibromatosis type 1
    • Down syndrome
    • Severe congenital anemia (i.e., Kostmann disease treated with granulocyte colony-stimulating factor)
    • Diamond-Blackfan anemia
    • Paroxysmal nocturnal hemoglobinemia
    • Li-Fraumeni syndrome
    • Shwachman-Diamond syndrome
    • Dyskeratosis congenita
    • Noonan syndrome (RASopathies)


  • Principal defect is a block in the differentiation of primitive myeloid precursor cells.
  • Two mechanisms predominate:
    • Defect at the level of transcriptional activation
    • Defects in the signaling pathway of hematopoietic growth factors. For example, the proto-oncogene Ras is mutated in up to 1/3 of patients with AML.


  • Exact cause unknown in most cases
  • Acquired risk factors include the following:
    • Exposure to benzene
    • Exposure to ionizing radiation
    • Therapy induced, from chemotherapy for a prior malignancy
    • Alkylating agents such as cyclophosphamide, nitrogen mustard, chlorambucil, and melphalan (typically presents several years after therapy)
    • Epipodophyllotoxins such as VP16, VM26 (typically occurs within 2 years after therapy and is characterized by rearrangements involving 11q23)

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