INTRODUCTION
Juvenile myelomonocytic leukemia (JMML) is a rare hematopoietic malignancy in children with features characteristic of both myelodysplastic and myeloproliferative disorders.1 In 2008, the World Health Organization (WHO) classified JMML into myelodysplastic syndrome (MDS) or myeloproliferative neoplasms (MPN).2 This rare disease has incidence rate of 1.2 per million children per year or 1% of all childhood leukemias.3 JMML is associated with two inherited diseases: neurofibromatosis type 1 (NF1) and Noonan syndrome.1 JMML affects young children with median age at diagnosis was 20-24 months and has a significant male predominance (2.5:1).4,5 Cytogenetic analysis of JMML patients showed monosomy 7 in 24-33% of patients, other chromosomal abnormalities in 10-27%, and normal karyotype in 40-60%.5
The symptoms of JMLL are fever and general malaise, plus symptoms due to infiltration of organs by malignant cells, infection, pallor, lymphadenopathy, marked hepatosplenomegaly, cutaneous lesions, and hemorrhagic manifestations. Hematologic abnormalities are caused by disruption of signal transduction in the RAS pathway.6Leukocytosis with monocytosis and myeloid/erythroid precursors, anemia, and thrombocytopenia are common findings in peripheral blood. The median blast cell percentage in peripheral blood is less than 2% and rarely exceeds 20%. Bone marrow abnormalities are non-specific and less informative than peripheral blood smear.5 JMML patients respond poorly to chemotherapy and probability to survival without allogenic hematopoietic stem cell transplantation (HSCT) is less than 10% or 10-12 months after diagnosis.5 Even after HSCT, 5-year event survival rate is only 44-53%.7Hereby we present a case report and brief literature review of JMML in a child, especially focused on applicability in low-middle income countries.