Introduction
Acute myeloid leukemia (AML) is a clinical and genetic heterogeneous disease that accounts for 15–20% of all childhood leukemias.1 Accurate diagnosis and treatment strategies have resulted in tremendous improvements in the overall survival (OS) rate of pediatric AML, which is now nearly 60%.2-5 Different subtypes of AML vary in clinical presentation characteristics and therapeutic effects. AML and hyperleukocytosis have been associated with an unfavorable prognosis,6,7 which can lead to a higher probability of early death due to complications of leukostasis, tumor lysis syndrome, and disseminated intravascular coagulation (DIC) .8
Hyperleukocytosis has no explicit diagnostic criteria so far, but usually refers to white blood cell (WBC) counts greater than 100×109/L in the peripheral blood of patients with acute leukemia.9 However, it should be noted that WBC counts below this arbitrary threshold can also cause leukocytosis-related complications. Hyperleukocytosis has been defined as more than 50×109/L in some studies in adults with AML.10-12To our knowledge, no study has reported the characteristics and prognosis of hyperleukocytosis (described as WBC count ≥50×109/L) in pediatric AML patients. The objective of our study was to contribute to recognizing this group of pediatric AML. In this study, we analyzed the clinical characteristics (sex, age, cytogenetics, molecular biology) and outcome in an unselected cohort of de novo non-M3 AML pediatric patients.