The patients usually present with a minimally productive or nonproductive cough, fever, and mild dyspnea on exertion. Acute symptoms suggest complicating infection. Pulmonary function tests show a restrictive defect, decreased diffusing capacity, and hypoxemia. The serum LDH is almost always increased.
Infection is the main complication.
The cause of the disturbance in surfactant turnover is unknown. The most consistently associated potential agents are dusts and fumes. The alveoli are filled with eosinophilic, proteinaceous material that closely resembles surfactant and shows a positive reaction on PAS staining. The alveolar septa are usually normal or slightly thickened. Interstitial fibrosis is uncommon.