Isolated central nervous system recurrence of acute promyelocytic leukemia in children

The incidence of isolated central nervous system (iCNS) relapse in pediatric acute promyelocytic leukemia (APL) is debated. We analyzed the literature, focusing on clinical trials reported since the advent of ATRA use. Only 2/218 (0.92%) good risk patients (diagnostic WBC <10,000/microl) had truly iCNS relapse. This incidence does not support the use of intrathecal CNS prophylaxis for all children with APL. We also identified multiple deficiencies in these reports. Additional reporting of these events could provide insight into the true incidence and pathogenesis of iCNS relapse and might allow for identification of risk factors associated with such extramedullary relapse.