Extramedullary Acute Myeloid Leukemia in the De Novo Setting: Clinicopathologic Characteristics, Molecular Analysis, and Treatment Outcomes

Abstract Extramedullary disease in acute myeloid leukemia (AML), also known as myeloid sarcoma (MS), is an uncommon presentation of de novo AML. We analyzed medical records of patients in the Mayo Clinic database spanning between 1996 and 2021 who were diagnosed with de novo extramedullary AML. Survival outcomes were analyzed using Kaplan-Meier and Cox-proportional hazard models for univariate and multivariate analysis, respectively. With a median follow-up of 20.7 months, 83 patients with de novo MS were identified; 49 presented with synchronous MS and 34 with isolated MS. Next generation sequencing (NGS) revealed RTK-RAS pathway mutations in 44% of patients. Median overall survival (OS) was 25.3 months and 17.8 months in isolated and synchronous MS, respectively (p = 0.49). Variables associated with improved OS on univariate analysis included treatment with intensive chemotherapy (p < 0.001), normal or favorable risk karyotype (p = 0.001), age less than 60 years (p = 0.001), and a complete response to treatment at extramedullary sites (p < 0.0001). On multivariate analysis, normal or favorable risk karyotype (p = 0.001), age less than 60 (p = 0.01), and a complete extramedullary response (p = 0.001) were associated with improved OS. Localized therapy did not provide added survival benefit in isolated MS. Genomic stratification, age, and extramedullary site response are predictive of survival outcomes.