How I treat hypereosinophilic syndromes.

Hypereosinophilic syndromes (HESs) are a heterogeneous group of uncommon disorders characterized by marked peripheral eosinophilia and end organ manifestations attributable to the eosinophilia or unexplained in the clinical setting. Whereas corticosteroids remain the mainstay of treatment for most patients, recent diagnostic advances and the development of novel targeted therapies, including tyrosine kinase inhibitors and humanized monoclonal antibodies, have increased the complexity of therapeutic decisions in HESs. This review presents a treatment-based approach to the diagnosis and classification of patients with peripheral blood eosinophilia of 1.5 x 10(9)/L (1500/mm3) or higher and discusses the role of currently available therapeutic agents in the treatment of these patients.