Hyperleucocytosis in paediatric acute myeloid leukaemia - the challenge of white blood cell counts above 200ￂ ×ￂ 109/l. The NOPHO experience 1984-2014

Summary Hyperleucocytosis in paediatric acute myeloid leukaemia (AML) is associated with increased morbidity and mortality. We studied hyperleucocytosis in 890 patients with AML aged 0-18 years registered in the Nordic Society of Paediatric Haematology and Oncology (NOPHO) registry, with special focus on very high white blood cell counts (WBC >200 × 10/l). Eighty-six patients (10%) had WBC 100-199 × 109/l and 57 (6%) had WBC ≥200 × 109/l. Patients with WBC ≥200 × 109/l had a high frequency of t(9;11) and a paucity of trisomy 8. Due to the high frequency of deaths within the first 2 weeks (30% vs. 1% for all others), overall survival in this group was inferior to patients with WBC