Definition of Pulmonary alveolar proteinosis:

Pulmonary alveolar proteinosis is a rare disease in which a type of protein builds up in the air sacs (alveoli) of the lungs, making breathing difficult.

Causes, incidence, and risk factors:

In some cases, the cause of pulmonary alveolar proteinosis is unknown. In others, it occurs with lung infection or an immune problem. It also can occur with cancers of the blood system, and after exposure to high levels of environmental substances, such as silica or aluminum dust.

This rare disorder generally affects people ages 30 - 50 and is seen in men more often than in women. A form of the disorder is present at birth (congenital).