Myeloid Sarcoma Predicts Superior Outcome in Pediatric AML; Can Cytogenetics Solve the Puzzle?

Background The purpose of our study was to evaluate the clinical, cytogenetic, and molecular features, and survival outcomes in patients with acute myeloid leukemia (AML) with myeloid sarcoma (MS) and compare them with patients with AML without MS. Patients and Methods This was a retrospective analysis of de novo pediatric AML patients with or without MS diagnosed at our cancer center between June 2003 and June 2016. Results MS was present in 121 of 570 (21.2%), the most frequent site being the orbit. Patients with MS had a younger median age (6 years vs. 10 years) and presented with higher hemoglobin and platelet but lower white blood cell count compared with patients without MS. Further, t (8; 21) ( P P P = .03) were significantly higher in patients with AML with MS. Event-free survival (EFS; P = .003) and overall survival (OS; P = .001) were better among patients with AML with MS (median EFS 21.0 months and median OS 37.1 months) compared with those with AML without MS (median EFS 11.2 months and median OS 16.2 months). The t (8; 21) was significantly associated with MS (odds ratio, 3.92). In a comparison of the 4 groups divided according to the presence or absence of MS and t (8; 21), the subgroup of patients having MS without concomitant t (8; 21) was the only group to have a significantly better OS (hazard ratio, 0.53; 95% confidence interval, 0.34-0.82; P = .005). Conclusion Although t (8; 21) was more frequently associated with MS, it did not appear to be the reason for better outcome.