Progress In Eosinophilic Disorders

Eosinophilic disorders are a group of heterogeneous diseases with complicated etiologies,pathogenesis and varied therapies.With the research on the pathogenesis of the disease,more and more subcategories are defined independently.With the deepening understanding of the disorders,the diagnosis and classification of the disorders are constantly updated.But the nomination and classification of the disorders with eosinophilia is still chaos so far,to some extent.The purpose of this article is to learn the idea of diagnosis and the related treatment by introducing the WHO classification of tumours of haematopoietic and lymphoid tissues and the classification of International Eosinophil Society,to ensure the clinical work to be more smoothly.After evaluation of secondary causes of eosinophilia,the 2008 World Health Organization devide eosinophilic disorders into four categories:myeloid and lymphoid neoplasms with eosinophilia and abnormalities of PDGFRA,PDGFRB or FGFR1,chronic eosinophilic leukemia,not otherwise specified(CEL-NOS),lymphocyte-variant hypereosinophilia(L-HE),and idiopathic hypereosinophilic syndrome(IHES).The 2008 WHO also proposed the diagnostic process of eosinophilic disorders.Fist,we should exclude reactive(secondary)causes of eosinophilia,such as parasitic infections,allergic diseases,connective tissue disease,lymphoma,etc.Second,we should evaluate for primary(clonal)eosinophilia through cytological examination,chromosome karyotype analysis and molecular biological methods.If the PDGFRA,PDGFRB or FGFR1 fusion gene is identified by FISH or RT-PCR or the rearrangenment of 4q12,5q31-33 or 8p11-13 is founded,we diagnose the disease with myeloid and lymphoid neoplasms with eosinophilia and abnormalities of PDGFRA,PDGFRB or FGFR1.A negative screen for PDGFRA/B-or FGFR1-rearranged but presence of a nonspecific clonal cytogenetic abnormality or increased blast cells(>2% in the peripheral blood or >5% in the bone marrow,but <20%)eosinophilias should lend consideration to a diagnosis of CEL-NOS.Third,Some patients may exhibit immunophenotypically aberrant T-cell population,for this part we diagnose with L-HE.Otherwise,we diagnose with idiopathic HE/HES.Be different with WHO,2010 international eosinophil societ devide eosinophilic disorders into six clinically defined groups to facilitate treatment decisions: myeloproliferative HE/HES(M-HE/HES),lymphocytic variant HE/HES(L-HE/HES),overlap HES,associated HE/HES,familial HE/HES and idiopathic HE/HES.Anyway,no matter what kind of type,the goal of therapy is to mitigate eosinophil-mediated organ damage.For patients with milder forms of eosinophilia(e.g.<1,500/mm3)without symptoms or signs of organ involvement,a watch and wait approach with close-follow-up may be undertaken.Identification of rearranged PDGFRA or PDGFRB is critical because of the exquisite responsiveness of these diseases to imatinib.Corticosteroids are first-line therapy for patients with L-HE and HES.Hydroxyurea and interferon-alpha have demonstrated efficacy as initial treatment and steroid-refractory cases of HES.In addition to hydroxyurea,second-line cytotoxic chemotherapy agents and hematopoietic cell transplant have been used for aggressive forms of HES and CEL-NOS with outcomes reported for limited number of patients.Although clinical trials have been performed with anti-IL-5(mepolizumab)and anti-CD52(alemtuzumab)antibodies,their therapeutic role has yet to be established.