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Respiratory bronchiolitis associated with interstitial lung disease
Last reviewed: 05.07.2025
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[ What causes respiratory bronchiolitis associated with interstitial lung disease?
Most smokers develop subclinical bronchiolitis, characterized by mild to moderate inflammation of the small airways. The few patients who develop more severe inflammation with clinically significant interstitial disease are considered to have respiratory bronchiolitis associated with interstitial lung disease (RBAILD). Men are affected twice as often as women. RBAILD is characterized by inflammation of the submucosa of the membranous and respiratory bronchioles, manifested by the presence of dark-brown pigmented macrophages (due to increased iron content similar to that seen in smokers), mucus congestion, and metaplastic cuboidal epithelium located in the bronchioles and alveoli. Damage to the alveolar septa is always present. These changes, however, also occur in some hypersensitivity reactions, occupational lung diseases (usually due to exposure to mineral dusts), viral infections, and drug reactions. Respiratory bronchiolitis associated with interstitial lung disease also resembles desquamative interstitial pneumonia histologically, but in RBAILD the inflammation is more focal and less extensive. The similarity of the two conditions has led to the suggestion that they are different variants of the same smoking-induced disease.
Symptoms of respiratory bronchiolitis associated with interstitial lung disease
Cough and dyspnea on exertion resemble those of other RBAILDs, especially IFL, but are less severe. The only physical examination finding is wheezing, detectable by auscultation.
Diagnosis of respiratory bronchiolitis associated with interstitial lung disease
Diagnosis is based on history, imaging, pulmonary function tests, and histologic examination of biopsy specimens. Chest radiographic findings include diffuse hyperarray or focal opacities; thickening of the bronchial walls; hyperplasia of peribronchial interstitial tissue; fine opacities of regular and irregular shape; and fine peripheral ring-shaped shadows. HRCT often reveals ground-glass opacities. Mixed obstructive-restrictive pulmonary function tests are typical, although results may be normal or indicate isolated increase in residual volume. Arterial blood gas analysis usually reveals moderate hypoxemia. Standard laboratory tests are uninformative.
Treatment of respiratory bronchiolitis associated with interstitial lung disease
Treatment of respiratory bronchiolitis associated with interstitial lung disease is smoking cessation; there is some evidence for the efficacy of glucocorticoids. The natural history of the disease is unknown, but the prognosis is good with smoking cessation.