Hyperleucocytosis in acute myeloid leukaemia

Hyperleucocytosis is generally defined as an initial white cell count/blast count of more than 100 x 10^9/l.

• if a high white cell count is seen at presentation it is considered to be a poor prognostic factor
• around 14% of patients have hyperleucocytosis at presentation and the risk of early death is greater when compared to patients presenting with a white cell count of <100 (15% vs. 5.4%) (1)
• it is also associated with increased induction mortality, with a majority caused by hemorrhagic events, tumor lysis syndrome, and infections (2)

Immediate medical treatment is required in hyperleukocytosis with leucostasis e.g. - in pulmonary infiltrates or in retinal and cerebral haemorrhages (2).

Leucopheresis is a safe procedure and is considered an option for the initial management in patients with AML presenting with symptomatic hyperleucocytosis

• benefits or impact on long-term outcome of this procedure have not been proven (1,2)
• it is contraindicated in suspected acute promyelocytic leukemia (APL) since it may exacerbate the coagulopathy with fatal consequences (1)

Generally, hydroxyurea (up to 50 to 60 mg/kg per day) is the recommended treatment to decrease the WBC count (to less than 10-20 × 109/L) (2).

It is important to consider the prevention of tumour lysis syndrome in these patients (2).

Reference:

• 1. British Committee for Standards in Haematology et al.Guidelines on the management of acute myeloid leukaemia in adults. Br J Haematol. 2006;135(4):450-74.
• 2. Döhner H et al. Diagnosis and management of acute myeloid leukemia in adults: recommendations from an international expert panel, on behalf of the European LeukemiaNet. Blood. 2010;115(3):453-74.