Study on Clinical and Laboratory Characteristics of Chronic Eosinophilic Leukemia CEL/Hypereosinophilic Syndrome (CEL/HES).
Authors: Xiao Zhijian , Zhang Yue , Wang JianXiang , Hao Yushu 
Published: October 2019

Abstract
Hypereosinophilic syndrome (HES) was a group of diseases associated with persistent eosinophilia without unknown causes, companied with tissue and organ impairments. In 2001, WHO classification of hematopoietic and lymphoid neoplasms classified chronic eosinophilic leukemia (CEL) / HES into the category of chronic myeloproliferative disease, and proposed that the principal basis for the identification of CEL and HES was whether to have the evidence of eosinophils clonal proliferation: CEL had the evidence of eosinophils clonal proliferation, while HES was lack of the evidence of eosinophils clonal proliferation. In this study, 20 cases of CEL/ HES patients were analyzed retrospectively, and nested RT-PCR was used to detect FIP1L1-PDGFRA (F/P) fusion gene; Allele-specific PCR (ASP) conjoint sequencing analysis was used to detect JAK2 V617F, and PCR-RFLP was adopted to detect the mutation status of JAK2 V617F; and PCR is applied to detect TCRγ rearrangement. The clinical and laboratory characteristics of CEL and HES were compared. The ratio of male and female in the 20 cases of patients was 19:1, and the median age was 33 (20–57). F/P detection was positive for 12 cases, and the sequencing confirmed that FIP1L1 break point was at intron 10–12, while PDGFRA break point was at exon 12. There was 1 case of patient found that had JAK2 V617F, and the mutation status analysis showed that it was the mutation on heterozygote. 6 cases were detected having TCRγ gene rearrangement, of which 4 cases were CEL patients, and other 2 cases were HES patients. Most of CEL patients had respiratory symptoms in the early stage, easily companied with circulatory systematic impairment and nervous systematic symptoms. The incidence of splenomegaly of CEL patients was obviously higher than that of HES patients (92.5% vs 42.5%, p=0.031), so did the incidence of anemia and myelofibrosis. There was no difference in EO, WBC, PLT and EO% in peripheral blood as well as bone-marrow eosinophils percentage and bone-marrow primitive cells’ percentage between two groups. Abnormal morphology of eosinophils was often found in CEL patients, with the main manifestation of eosinopenia, basopenia and plasma vacuoles. Our data showed that
Eosinophilia is often caught by male, mainly by the young; CEL patients have the main manifestation of the circulatory systematic, respiratory and gastrointestinal symptoms, and have a high incidence of anemia and thrombocytopenia. The routine examination has a little significance for the identification o CEL and HES, while the bone marrow smears morphological examination has a certain help for the diagnosis of CEL; Some HES patients have JAK2 V617F mutation, and further studies on the effect of JAK2 V617F mutation on the pathogenesis of HES can contribute to the diagnosis of such patients in the future and the development of the new targeted drug therapy; Some CEL patients have TCRγ rearrangement, while the relationship of CEL and TCRγ needs a further study.