Nonasthmatic eosinophilic bronchitis mimics asthma.

In the May issue of the Journal, King and Moores1 presented a very nice overview of asthma phenotypes and disorders that mimic asthma. That article was followed by a paper by McCormack and Enright2 that reviewed the process of making a diagnosis of asthma, including a brief overview of the differential diagnosis of asthma. I respectfully submit that missing from both papers is a description of nonasthmatic eosinophilic bronchitis, which is a very important asthma “masquerader.” First described by Gibson and colleagues3 in 1989, nonasthmaticeosinophilicbronchitis is characterized by chronic cough and sputum eosinophilia but without the airflow obstruction and bronchial hyperresponsiveness of asthma.3,4 Nonasthmatic eosinophilic bronchitis can easily be misdiagnosed as asthma because it responds readily to corticosteroids, just like asthma. We found a large percentage of patients being treated with inhaled corticosteroids prior to a definitive diagnosis of asthma being made.5 It is therefore not difficult to understand how patients with chronic cough can be wrongly diagnosed with asthma, based solely on a positive response to an empirical trial of inhaled corticosteroids. Nonasthmatic eosinophilic bronchitis is far from uncommon. In a study of patients with chronic cough, Brightling et al6 found that nonasthmatic eosinophilic bronchitis was the cause of cough in 13% of the patients. Nonasthmatic eosinophilic bronchitis is a common cause of chronic cough and is an important part of the differential diagnosis of asthma.