Last edited 05/2019 and last reviewed 05/2019

Leukaemias are:

  • malignant neoplasms of the haemopoietic stem cells
  • primary neoplasms of the bone marrow

The malignant cells gradually replace the normal bone marrow and may spill over into the peripheral circulation.

Leukaemias may be divided into:

  • acute leukaemias:
    • show rapid proliferation of relatively undifferentiated malignant cells
    • are characterised by the development of bone marrow failure with consequent anaemia, neutropenia, and thrombocytopenia
    • are the most common leukaemias among children

  • chronic leukaemias:
    • have a relatively prolonged natural history
    • are characterised by better differentiated malignant cells
    • compromise marrow function at a late stage
    • have features of the large load of malignant cells e.g. hepatosplenomegaly
    • are rare in children

Leukaemia is the most common childhood malignant disease - with an incidence of 3.5 per 100,000 per year in children under the age of 15 years. But as a whole, it is more common in the elderly - 60% occuring in patients over 50 years of age.