Disseminated MRSA and Myelokathexis Preceding AML with t(8;21) and ASXL1 Mutation

Pediatric acute myeloid leukemia (AML) is heterogeneous, and molecular genetics strongly influence prognosis. Although t(8;21) AML is considered favorable, additional mutations such as ASXL1 can worsen outcomes. We report a 13-year-old boy with 2 months of fever, pancytopenia, and disseminated MRSA abscesses. Bone marrow showed myelokathexis but no blasts. Immunological evaluation excluded WHIM syndrome and inborn errors of immunity. After infection control and transient hematologic recovery, the child relapsed with recurrent fever and cytopenia. Peripheral smear revealed 85% myeloblasts; bone marrow confirmed AML with t(8;21), monosomy Y, del(9q), and ASXL1 mutation. He achieved remission with cytarabine-based induction and consolidation, but hematopoietic stem cell transplantation (HSCT) was declined. This case illustrates the diagnostic challenge of prolonged cytopenia and infection preceding AML. Myelokathexis suggested immune dysfunction but ultimately represented an early clonal abnormality. Although t(8;21) is favorable, ASXL1 mutation confers high-risk biology, supporting HSCT in first remission. Children with unexplained cytopenia require vigilant monitoring and genomic profiling. Integration of molecular risk factors should guide individualized treatment strategies.