This disease affects mainly children but can also affect adults. Some of the blood that leaks out of the capillaries is taken up by scavenger cells in the lung. The breakdown products of the blood irritate the lung and lead to scarring. The frequency and severity depend on how often the capillaries bleed into the lungs. After the lungs become scarred, shortness of breath develops.
Treatment is aimed mostly at relieving symptoms.
Corticosteroids and cytotoxic drugs such as azathioprine may help during flare-ups. Blood transfusions may be needed for blood loss, and oxygen therapy may be needed for a low level of oxygen in the blood. The disease generally affects people between ages 20 and 60 who aren't known to have lung disease. The cause of pulmonary alveolar proteinosis is unknown. In rare instances, lung tissue becomes scarred.