Transient abnormal myelopoiesis in non‐Down syndrome neonate

We encountered a case of neonatal acute megakaryoblastic leukemia not associated with Down syndrome (DS). Molecular cytogenetic analysis of leukemic blast cells indicated that increased blast cell status was caused by transient abnormal myelopoiesis with trisomy 21 and GATA1 mutation. Based on these molecular cytogenetic data, intensive chemotherapy was avoided, and the patient was successfully cured with low‐dose cytarabine. Morphologically, leukemic blast cells of acute megakaryoblastic leukemia in a non‐DS neonate are indistinguishable from a blast cell of transient abnormal myelopoiesis. The possibility of transient abnormal myelopoiesis should be carefully considered before intensive chemotherapy is adopted.