Benign Eosinophil Disorders

Eosinophilia can be seen in almost all medical subspecialty patients. Causes of hypereosinophilia (HE) are diverse and can be grouped under 3 categories: primary (neoplastic), secondary (reactive), and idiopathic. Advances in molecular genetic diagnostics have led to elucidation of the genetic basis for many neoplastic hypereosinophilic disorders. Diagnostic evaluation of HE involves a combination of clinical, histopathologic, and immunophenotypic analyses, as well as molecular genetic testing, including next-generation sequencing–based mutation panels. The management of HE is largely guided by the underlying etiology and molecular genetic abnormalities.