Advances in the diagnosis and treatment of eosinophilia.

Purpose of Review: Eosinophils play an important role in the pathogenesis of allergic, infectious and malignant diseases. Over the last decade, new diagnostic tools and treatment modalities have led to the re-evaluation of the existing definition of eosinophilic disorders. This review discusses a recent proposal for new terminology and classification of hypereosinophilia. The results of targeted therapy for hypereosinophilia-related disorders are also summarized.
Recent Findings: A panel of multidisciplinary experts agreed on unifying definitions and criteria of eosinophilia-associated disorders and created a new classification of hypereosinophilia-related conditions based on clinical, haematological and laboratory findings as well as the underlying cause of hypereosinophilia. Recent results of the treatment of idiopathic hypereosinophilic syndrome (HES) with the anti-interleukin 5 monoclonal antibody mepolizumab showed its efficacy and manageable safety profile. The treatment of platelet-derived growth factor alpha (PDGFRA)-positive HES with imatinib demonstrated long-lasting efficacy and low likelihood of drug resistance.
Summary: The unifying terminology and definitions should aid physicians caring for patients with hypereosinophilia. Despite much progress, serum biomarkers correlate with disease severity and predict responses to treatment that are needed. There is also a great need for understanding and specific therapy for PDGFRA-negative HES.