Pediatric Cancer in Africa by Daniela Cristina Stefan & Mhamed Harif

Author:Daniela Cristina Stefan & Mhamed Harif
Language: eng
Format: epub
Publisher: Springer International Publishing, Cham

Juvenile Myelomonocytic Leukemia

Juvenile myelomonocytic leukemia (JMML) is more common in patients with type-1 neurofibromatosis, Noonan syndrome (facial dysmorphia, dwarfism, mental retardation, and congenital heart disease) and Trisomy 8 (mental retardation, various dysmorphias, genitourinary malformations). Monosomy 7 may also be found.

The main biologic abnormality is a hypersensitivity of stem cell to cytokines stimulation, in particular, GM-CSF, TNF, and IL-1 b. Autocrine production contributes to spontaneous cell proliferation in vitro. Gene RAS activation seem to be the origin of this anomaly.

This disease is mainly encountered in children younger than 2 years of age. Clinical manifestations include pallor, respiratory signs, hemorrhagic syndrome, skin lesions (rash, eczema, and xanthoma), an enlarged spleen and/or hepatomegaly, lymphadenopathy or diarrhea. The hemogram shows leukocytosis with monocytosis, thrombocytopenia, erythro-myelemia, occasionally blasts. The bone marrow smears consists in hyperplasia of granulocyte lineage with signs of myelodysplasia involving granulocytic and megakaryocytic lineage and often a moderate blasts infiltration. Electrophoresis of hemoglobin is dominated by a high hemoglobin F level. The cytogenetic exploration does not show specific anomaly and in particular absence of translocation t(9, 22).

This disease is usually associated with a poor prognosis. 6-mercaptopurine with or without low-dose aracytine or more intensive regimen, similar to those used in acute myeloblastic leukemia reduce blast cell count and improve the quality of life but have no impact on survival in the JMML. Hematopoietic stem cell transplantation from a compatible family donor allows 50 % long-term survival. The use of 13 cis-retinoic acid inhibit in vitro monocytic proliferation but the response is however transient.

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