Last reviewed 01/2018

Acute promyelocytic leukaemia (APL) is a distinct subtype of AML which is characterised by the presence of many promyelocytes in peripheral blood and marrow aspirate.

Promyelocytes are:

  • cells with a granular cytoplasm which stains brown with myeloperoxidase
  • normally precursors of neutrophils, basophils, eosinophils and monocytes

APL accounts for approximately 5-15% of acute myeloid leukaemia (1).

The following are considered independent risk factors for the development of APL in a patient with AML:

  • younger age
  • Hispanic background
  • obesity (1)

The major cause of mortality is bleeding, particularly intracranial, which may be exacerbated by chemotherapy.

Although relatively rare, APL is important since it is the first cancer in which a specific treatment has been developed which targets the genetic defect responsible for tumorigenesis.