pulmonary disorders
Respiratory Bronchiolitis–Associated Interstitial Lung Disease
Introduction
Respiratory bronchiolitis–associated interstitial lung disease (RBILD) is a syndrome of small airway inflammation and interstitial lung disease occurring in people who smoke. Symptoms include cough and breathlessness during exertion. Chest x-ray, high-resolution CT, and sometimes lung biopsy are needed for diagnosis. Treatment is smoking cessation. Respiratory bronchiolitis–associated interstitial lung disease is a form of Overview of Idiopathic Interstitial Pneumonias . Most people who smoke develop a subclinical bronchiolitis characterized by mild or moderate inflammation of the small airways. The few patients who develop more severe inflammation with clinically significant interstitial disease are said to have RBILD. Male-to-female ratio is 2:1. RBILD is characterized histologically by submucosal inflammation of the membranous and respiratory bronchioles manifested by the presence of tan-brown pigmented macrophages (resulting from increased iron content, as occurs in smokers), mucus stasis, and metaplastic cuboidal epithelium in bronchioles and alveoli. Alveolar septal scarring always occurs. Similar findings, however, occur in some hypersensitivity reactions, Hypersensitivity Pneumonitis (usually due to mineral dusts), viral infections, and drug reactions. RBILD also resembles Desquamative Interstitial Pneumonia histologically, but in RBILD, inflammation is patchier and less extensive. The similarity of the 2 conditions has led to the suggestion that they are different manifestations of the same disease caused by cigarette smoking. Symptoms of cough and breathlessness during exertion resemble those of other interstitial lung diseases, especially Idiopathic Pulmonary Fibrosis , but are milder. Crackles on examination are the only physical finding. 