Early T-Cell Precursor Acute Lymphoblastic Leukemia in an Infant With an NRAS Q61R Mutation and Clinical Features of Juvenile Myelomonocytic Leukemia.

Early T-cell precursor acute lymphoblasticleukemia (ETP- ALL) is a subtype of T-acute lymphoblasticleukemia (T- ALL) arising from a primitive precursor. We present a unique case of an infant with ETP- ALLwith a missense NRAS mutation in codon 61 (c.182A>G, p.Q61R). The patient also had a minor population of non-ETP T- ALLblasts and clinical features typically associated with juvenile myelomonocytic leukemia(JMML), namely, absolute monocytosis, splenomegaly, and elevated hemoglobin F. The treatment was initiated with chemotherapy, followed by cord blood transplantation. The patient achieved remission, but unfortunately died from transplant-related complications. This case highlights an NRAS mutation in ETP- ALLwith JMML-like phenotype.