Inflammation and thickening of the walls of the alveoli (tiny air sacs) in the lungs. Alveolitis reduces the elasticity, and therefore the efficiency, of the lungs. It is most commonly due to an allergic reaction to inhaled dust of animal or plant origin, as in farmer’s lung, bagassosis, and pigeon fancier’s lung (due to particles from bird droppings). Fibrosing alveolitis is an autoimmune disorder. In some cases, it occurs with other autoimmune disorders such as rheumatoid arthritis or systemic lupus erythematosus. Radiation alveolitis is caused by irradiation of the lungs and may occur as a rare complication of radiotherapy for lung or breast cancer. Alveolitis usually causes a dry cough and breathing difficulty on exertion. A chest X-ray, blood tests, pulmonary function tests, or a lung biopsy may be needed to diagnose alveolitis. For most types of alveolitis, a short course of corticosteroid drugs relieves symptoms, but for fibrosing alveolitis these may need to be taken indefinitely. If the cause of allergic alveolitis is recognized and avoided before lung damage occurs, the effects are not permanent. In fibrosing alveolitis, damage progresses despite treatment, causing increasing breathing difficulty and, sometimes, respiratory failure.


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