Early complications in children with acute lymphoblastic leukemia presenting with hyperleukocytosis.

Background: The optimal management of childhood acute lymphoblastic leukemia (ALL) with hyperleukocytosis is unclear, largely because the risk of leukostasis-related complications is poorly characterized.

Procedure: We reviewed the presenting characteristics, initial management, and frequency and type of complications in all children seen at St. Jude Children's Research Hospital with previously untreated ALL and an initial leukocyte count >200 x 10(9)/L.

Results: A total of 178 children, representing 8% of all children with ALL, had an initial leukocyte count >200 x 10(9)/L; 67 patients had a leukocyte count >400 x 10(9)/L. Sixteen patients (9%) had neurological complications with 12 of these patients experiencing symptoms at presentation. Four patients (2%), all with initial leukocyte counts >400 x 10(9)/L, suffered a CNS hemorrhage. Pulmonary leukostasis occurred in 11 patients (6%). The degree of hyperleukocytosis was significantly predictive of neurological (P = 0.006) and respiratory (P = 0.014) complications. The majority of complications occurred at presentation. Cytoreduction (94 patients) decreased the leukocyte count but delayed initiation of chemotherapy (P = 0.013).

Conclusions: Serious leukostasis-related complications are relatively uncommon in childhood ALL and most occur at presentation. Their incidence increases in proportion to the leukocyte count. A large subset of cases can be managed successfully without cytoreduction. Cytoreduction may be considered for patients with leukocyte counts >400 x 10(9)/L or patients who have complications at presentation.