Churg-Strauss syndrome: update on clinical, laboratory and therapeutic aspects

Originally described over fifty years ago as a disorder of asthma, eosinophilic inflammation and small vessel vasculitis, Churg-Strauss syndrome is now defined as one of the ANCA-associated vasculitides. The predilection of disease manifestations for the respiratory tract, preferred affliction of small vessels including capillaries, and the frequent occurrence of anti-neutrophil cytoplasmic antibodies (ANCA) justify this grouping together with Wegener's granulomatosis and microscopic polyangiitis. However, the allergic background in which the vasculitis presents, typically characterized by asthma and prominent peripheral blood and tissue eosinophilia, render it unique among the primary systemic vasculitis syndromes. Despite recent interest in a potential link between leukotriene receptor antagonist use for asthma and the onset of Churg-Strauss syndrome, it remains a rare disease with poorly understood pathogenesis. This review provides an update on the clinical diagnosis of Churg-Strauss syndrome in light of changing disease definitions and classifications, and focuses on evolving therapeutic approaches for this challenging systemic disorder.