[Hypereosinophilic syndrome and Churg-Strauss syndrome: is it clinically relevant to differentiate these syndromes?].

Churg-Strauss syndrome and the hypereosinophilic syndrome share many clinical features, particularly in the early disease stages. Beside blood and tissue eosinophilia, peripheral neuropathies, cutaneous manifestations, eosinophilic alveolitis and gastroenteritis are frequently found. In contrast to the hypereosinophilic syndrome, Churg-Strauss syndrome is defined by the presence of systemic vasculitis. However, frequently symptoms related to eosinophilia are (mis)interpreted as indirect signs of vasculitis. New treatment modalities and diagnostic methods render the early differentiation between Churg-Strauss syndrome and the hypereosinophilic syndrome increasingly clinically important. Patients with hypereosinophilic syndrome should be tested for the presence of the FIP1L1-PDGRFA-mutatition in order to identify patients that could benefit from a treatment with a tyrosine kinase inhibitor such as Imatinib. At present, immunosuppression is still the treatment of first choice for Churg-Strauss syndrome. Novel treatment modalities for both diseases include immunomodulation with interferon alpha and biologics such as antibodies against interleukin 5.