A 55-year-old man with severe persistent asthma poorly responsive to asthma therapy.

Asthma is often triggered by allergic and nonallergic factors in atopic individuals and readily responds to anti-inflammatory and bronchodilator therapy. The differential diagnosis for poorly responsive disease includes severe persistent asthma with associated allergic rhinitis, cardiac disorders such as left ventricular failure or mitral stenosis, vocal cord dysfunction, gastroesophageal reflux disease, recurrent aspiration, chronic obstructive pulmonary disease, emphysema, alpha-1-antitrypsin deficiency, sarcoidosis, hypersensitivity pneumonitis, bronchiectasis, allergic bronchopulmonary aspergillosis, airway neoplasm, and Churg-Strauss vasculitis. A careful history and physical in conjunction with appropriate screening of laboratory information will usually direct the clinician to the correct diagnosis.