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.