Case report: rapid and complete control of idiopathic hypereosinophilia with imatinib mesylate.

In this case report, we report what we believe to be the first case of imatinib mesylate or STI-571 (Novartis) use for treatment of idiopathic hypereosinophilia syndrome (HES). HES is often a fatal illness, damaging the heart, nervous system, lungs, liver, and kidneys. It is often treated with interferon-alpha. In this patient, it was combined with hydroxyurea, and we believe it saved his life. However, he experienced many common side effects, such as a profound intractable headache, severe fatigue, and concentration difficulties. After years on hydroxyurea and interferon-alpha, the severity of these side effects motivated us to try a trial of imatinib mesylate. Its use was followed by an abrupt remission of HES in a few weeks, with no significant side effects.