Myeloid sarcoma is associated with poor clinical outcome in pediatric patients with acute myeloid leukemia

Purpose The impact of myeloid sarcoma (MS) on clinical outcome of pediatric acute myeloid leukemia (AML) patients remains controversial. Moreover, little is known about the role of stem cell transplantation (SCT) in such patients. Methods Clinical data of patients with AML under 18 years of age were retrieved from the TARGET dataset. We analyzed the prevalence, clinical profile, molecular characteristics, and prognosis of MS in these patients. Results Among 884 pediatric patients with AML, the frequency of MS was 12.3%. Pediatric AML with MS was associated with age under 1-year, abnormal cytogenetics, and KMT2A rearrangement. Moreover, MS was associated with a low complete remission rate, high induction death, poor 5-year EFS, and OS. KMT2A rearrangement had a negative impact on clinical outcome in AML patients with MS. In addition, SCT had no significant effect on the survival of AML patients with MS. Multivariate analysis revealed that MS was an unfavorable prognostic factor in pediatric AML in terms of EFS (Hazard ratio 1.670, P < 0.001) and OS (Hazard ratio 1.623, P = 0.004). Conclusions The presence of MS at diagnosis of pediatric AML is associated with poor clinical outcomes, particularly when associated with KMT2A rearrangements. Moreover, pediatric patients with AML and MS may not benefit from SCT.