Churg-Strauss vasculitis and idiopathic hypereosinophyl syndrome: role of molecular biology in the differential diagnosis of hypereosinophyl syndrome

Objective: Hypereosinophilic syndromes are a heterogeneous group of uncommon disorders characterized by the presence of marked peripheral blood eosinophilia, tissue eosinophilia, or both, resulting in a wide variety of clinical manifestations, often without an identifiable cause. Churg-Strauss syndrome is a systemic vasculitis characterized by prominent peripheral eosinophilia, asthma and systemic involvement. The presence of mild to severe eosinophilia and systemic involvement raise the search of many trigger factor that need to be ruled out. Distinguishing CSS from idiopathic hypereosinophilic syndrome may be particularly challenging, especially in ANCA negative patients. Methods: The aim of the present study was to present a small case series of patients referred to a Rheumatology Unit for mild to severe eosinophilia and signs and symptoms of systemic involvement and to outline the clinical significance of molecular biology in the work-up of hypereosinophilia. Results: Eleven patients with moderate to severe peripheral eosinophylia, were referred to our Unit from 1996 to 2007. Female to male ratio was 7/4, mean age 40.54 (range 22-75). Three out of eleven patients resulted positive for molecular biology. The diagnosis of idiopathic hypereosinophylia was confirmed in one out of three on the basis of the clinical picture and bone marrow biopsy. Conclusions: Molecular biology may be useful in the screening and in the follow-up of a new hypereosinophylic patient.