Progresses In Studies On Juvenile Myelomonocytic Leukemia Attaching Three Cases Report

Objective:JMML is a rare disease with a low incidence in childhood leukemia. Three patients were diagnosed with JMML in recent 3 years in Children's Hospital, Chongqing Medical University. The clinical manifestation, laboratory findings and the diagnosis were summarized and analyzed. The references were reviewed. The purpose of this study is aimed to help clinicians to study the JMML and make the right diagnosis. Methods: Following the suspected patients with JMML, read the patients charts, completed the diagnosis study in lab, reviewed the references on JMML widely, make the diagnosis finally.Results: Two male patients and one felmale patient were diagnosed with JMML from September in 2008 to April in 2011. The age of the patients were at 2 months, 8 months and 8 months. All of them had apparent respiratory infections, and cough was especially serious. Fever, pale, skin-infiltration, hemorrhage, hepatomegaly, splenomegaly and lymphadenectasis were oberserved. Leukocytosis, absolute monocytosis, anemia, thrombocytopenia and the increasing of circulating myeloid precursors were found in the peripheral blood of the patients. One of the patients presented with elevated HbF. The typical feature of the nuclear cell hyperplasia hyperactivity and the proportion of blasts less than 20% were found in the bone marrow of the three patients. Ph chromosome and BCR/ABL fusion gene were all absence. Chromosome -7 and 7q- were detected in the two patients. One patient had performed sibling matched HSCT after the diagnosis and have been followed 2 year in health.Conclusion:The three patients whose clinical manifestation fulfilled the diagnostic criteria of the JMML by international JMML Working Group Meeting in 1997 were diagnosed with the JMML. The patients with JMML shared characteristics of both MDS and MPD. The abnormality of the Ras signal pathways is the most important pathogenesis in JMML. More than one half of patients were diagnosed within 2 years old and the male were dominant. The early clinical features of JMML is varied. Most of the patients starts with respiratory infections, accompanied with the virus infection. Skin biopsy can help diagnosis on the early-stage. Peripheral blood smear is the same important as the bone marrow smear for the diagnosis. Both of the Ph chromosome and BCR/ABL fusion gene are absence in JMML. Essentially JMML is resistant to all of the chemotherapy regimens. Presently the only curative therapy is allogenetic HSCT, but the incidence of the relapse is up to 50%. A significant number of JMML patients do achieve complete remission and long-term cure after a second bone marrow transplantation. The relation between mutational status and JMML clinical features, prognosis and relapse is not completely clear and it needs further study, the same with gene therapy. JMML is such a rare disease that multicenter joint research is prominent important to improve the diagnosis and prognosis.