Hypereosinophilic syndromes.

Hypereosinophilia (>0.5x10(9)/L) is a common clinical finding that can be secondary to a large variety of diseases (helminth infections, allergic diseases, drug reactions, specific organ disease, malignancies, systemic diseases). When a complete evaluation of a chronic hypereosinophilia fails to reveal an underlying disease, the diagnosis of hypereosinophilic syndrome (HES) or Churg-Strauss syndrome (CSS) is suggested.