Hogg and colleagues (21) in 1968 first used the term small airways disease to describe airway disease in patients with variably severe chronic airflow obstruction characterized by loss of bronchioles, mucus plugs, and variable amounts of inflammation and fibrosis that involve "the smallest bronchi as well as the bronchioles, so that neither bronchitis nor bronchiolitis is an appropriate term." Disease severity was noted to correlate with occlusion of airway lumen by mucus and inflammatory cells.
Although etiologies are numerous, small airways disease may be generally divided into small airways disease related to tobacco; to various other exposures, including mineral dusts; to diseases involving other areas of the lung, with secondary bronchiolar involvement; and to idiopathic causes.
Diffuse panbronchiolitis, an idiopathic, bilateral, progressive, obstructive, suppurative small airways disease associated with sinusitis, primarily occurs in Japan, has been increasingly identified within other Asian populations, and is uncommon in the United States.
Constrictive bronchiolitis, also termed bronchiolitis obliterans and obliterative bronchiolitis, is an obstructive small airways disease identified in a variety of disorders (Table 10).
Obliterative bronchiolitis: individual CT signs of small airways disease and functional correlation.