The seven biopsies revealed multiple, partly repeating and mixed histologic patterns, a) Small airways disease was present in almost all cases at different levels of severity, and we highlight patients D and F, in whom it was the main finding.
The frequency of small airways disease described in epidemiologic studies of WTC responders and the slow and relatively mild progression and long survival of the patients, which now appear to be exceeding survival of some with idiopathic interstitial lung disease, suggest that exposures at the WTC site might have caused these findings.
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.
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).
Although uncommon conditions such as diffuse idiopathic neuroendocrine cell hyperplasia and diffuse panbronchiolitis have histologic features that allow for relatively specific diagnoses, and although some conditions such as mineral dust-associated small airways disease, RBILD, granulomatous bronchiolitis, eosinophilic bronchiolitis, and fol licular bronchiolitis have histologic features that may be diagnostic in the appropriate clinical and radiologic setting, most cellular and fibrotic changes found in small airways disease are nonspecific.