Chronic Eosinophilic Leukemia/ Hypereosinophilic Syndrome
The eosinophil was histopathologically characterized in 1879 by Paul Ehrlich who mastered the use of aniline dyes to distinguish cell types (1). The term “eosinophil” was thus borne from the observation that the acidic dye eosin reacted strongly with the abundance of highly basic proteins found within the granules of these cells. Eosinophils serve a central function in the host defense against helminth infections and undergo recruitment and activation in allergic and inflammatory responses. However, as part of the immune system’s effort to maintain normal homeostasis, the potential for collateral tissue damage by eosinophils exists. This chapter focuses on the relatively rare but fascinating hematologic diseases: chronic eosinophilic leukemia (CEL) and hypereosinophilic syndrome (HES). These entities share a common theme of abnormal persistent elevation of the eosinophil count and the potential for substantial morbidity and mortality from organ complications. The study of pathologic hypereosinophilia was originally rooted in descriptive and morphologic investigations; however, with an increasingly sophisticated understanding of the cellular and molecular bases of these eosinophilic disorders, new biologically oriented classification schemes have emerged that carry therapeutic implications.
KeywordsChronic Myelogenous Leukemia Imatinib Mesylate Systemic Mastocytosis Hypereosinophilic Syndrome Chronic Myeloproliferative Disorder
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