2 ︳PATIENTS AND METHODS
Patients with pre-BLL included in this study were diagnosed and treated in the Shanghai Children’s Medical Center (SCMC) from January 2001 to December 2020. The diagnosis was determined by cell morphology, flow-cytometric and molecular biologic analysis. The diagnostic criteria were based of French–American–British (FAB) classification and European Group for the Immunological Characterization of Leukemias criteria5, 6. The presence of c-MYC arrangement was confirmed by fluorescence in situ hybridization (FISH). Patient data analyses included basic clinical information: gender, age and extramedullary infiltration; laboratory information: white blood cell count, serum UA, LDH level; and details of treatments and outcomes. This study was approved by the institutional review board of the SCMC.