Clinical Characteristics, Molecular Analysis and Survival Outcomes of Patients With Extramedullary Acute Myeloid Leukemia: A Retrospective Single-Center Study.

[BACKGROUND] Extramedullary acute myeloid leukemia (eAML) is a rare subtype of AML. The clinical features, molecular mechanisms and prognosis of eAML remain controversial. This study aimed to systematically analyze the differences in clinical and molecular characteristics between eAML patients and AML patients, and evaluate the impact of this disease subtype on survival outcomes.

[METHODS] We retrospectively included 96 patients with eAML and 144 patients with AML from our center between 2015 and 2024.

[RESULTS] eAML patients had a higher tumor burden than AML patients, with significantly elevated white blood cells (P < .001), platelets (P < .001), LDH (P < .001), peripheral blood blasts (P < .001) and bone marrow blasts (P = .005). In terms of molecular genetics, the eAML group was enriched for TET2, DNMT3A, ASXL1, PTPN11 and KMT2A mutations, while NPM1 and U2AF1 mutations were uncommon. The median overall survival (20.1 months vs. 38.8 months, P = .0021) and median relapse-free survival (7.6 months vs. 20.8 months, P = .00027) were significantly shorter for eAML patients. KRAS mutations and chromosomal abnormalities of t(9;11) were associated with poor prognosis. Allogeneic hematopoietic stem cell transplantation (Allo-HSCT) could improve the prognosis of eAML patients. In subgroup analysis, we found that patients with multiple extramedullary involvements, synchronous eAML, skin infiltration, and soft tissue involvement had a worse prognosis, while patients with central nervous system (CNS) infiltration had a better prognosis.

[CONCLUSION] Our study demonstrates that patients with eAML subtype have a worse prognosis, unique molecular features and higher tumor burden. Allo-HSCT might be an effective way to improve prognosis. This study provides evidence critical for risk stratification and treatment optimization in eAML.