Hyperleukocytosis

Abstract

Hyperleukocytosis (HL) is defi ned as a white blood cell (WBC) count >100 × 10 9 /L and in pediatric patients is typically seen in acute lymphoblastic leukemia (ALL), acute myelogenous leukemia (AML) and chronic myelogenous leukemia (CML). Although signifi cant gains have been made in the treatment of pediatric leukemia, HL continues to pose risk both in regard to early death and decreased overall survival. Patients with HL are at risk for acute complications due to rapid proliferation of leukemic blasts resulting in leukostasis and tumor lysis syndrome (TLS) as well as blast cell lysis leading to the release of anti-and procoagulant factors. The degree of HL that is clinically signifi cant in pediatric ALL and AML is controversial. Here we consider the differing presentations in patients with HL and concomitant ALL, AML, and CML and potential WBC thresholds at which patients require supplementary supportive care measures in an attempt to reduce early morbidity and mortality. In addition to an analysis of the evidence behind standard care measures, the potential benefi t of leukapheresis will be examined and recommendations given.