Seminars in respiratory and critical care medicine
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Diseases of the airway are common and make up a significant proportion of the respiratory physician's workload. The major contributors to this situation, such as asthma, chronic obstructive pulmonary disease (COPD), and chronic cough, all result from airway inflammation and often have an overlapping clinical picture, which in some instances makes accurate clinical diagnosis difficult. Asthma is a condition characterized by variable airflow obstruction, airway hyper-responsiveness, and airway inflammation, which is usually eosinophilic. ⋯ COPD has generally been considered to be a neutrophilic disease, in contrast to asthma. However, there is increasing evidence that a significant subgroup exists consisting of patients with stable COPD who have chronic airway eosinophilia with a more steroid-responsive disease. This article covers the role of eosinophils in the airway disorders asthma, COPD, and eosinophilic bronchitis.
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Churg-Strauss syndrome was originally called "allergic granulomatosis and angiitis," describing the combination of eosinophilic inflammation, extravascular granulomas, and necrotizing vasculitis occurring in patients with severe asthma. It is now classified as a small-vessel vasculitis and, together with Wegener's granulomatosis and microscopic polyangiitis, as one of the vasculitides associated with antineutrophil cytoplasmic autoantibodies (ANCA). Glucocorticoid-sparing agents used in the treatment of asthma, such as leukotriene receptor antagonists, may unmask this particular form of vasculitis as oral glucocorticoids are withdrawn. ⋯ Treatment consists primarily of glucocorticoids. Patients who have ANCA at the time of presentation should be treated according to the treatment principles for ANCA-associated vasculitides. However, the exact role of glucocorticoid-sparing immunosuppressive agents and treatment options for refractory disease remain poorly studied.