[Interpreting hypereosinophilia]

The diagnosis of a blood hypereosinophilia requires a review of various disease processes such as blood dyscrasias, skin diseases, auto-immune diseases, asthma, parasitic infections, enteropathies, etc. A complete check-up including clinical, laboratory and radiological data allows the identification of an etiology in a majority of cases. Nevertheless, the etiology of hypereosinophilia remains obscure in some cases. Among these unexplained situations, the rare idiopathic hypereosinophilic syndrome requires special attention because of its fatal course due to cardiac involvement which can remain clinically silent for a long period of time. Therefore, the follow-up should include repeated echocardiograms. At the present time, the usual therapy for the most severe cases includes corticosteroids and hydroxyurea.