Pulmonary alveolar proteinosis (PAP) is a rare disease in which a type of protein builds up in the air sacs (alveoli) of the lungs, making breathing difficult. Pulmonary means related to the lungs.
PAP; Alveolar proteinosis; Pulmonary alveolar phospholipoproteinosis; Alveolar lipoproteinosis phospholipidosis
In some cases, the cause of PAP 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.
People between 30 and 50 years old are most often affected. PAP is seen in men more often than in women. A form of the disorder is present at birth (congenital).
Symptoms of PAP may include any of the following:
Sometimes, there are no symptoms.
Treatment involves washing out the protein substance from the lung (whole-lung lavage) from time to time. Some people may need a lung transplant. Avoiding dusts that might have caused the condition is also recommended.
Another treatment that may be tried is a blood-stimulating drug called granulocyte-macrophage colony stimulating factor (GM-CSF), which is lacking in some people with alveolar proteinosis.
More information and support for people with pulmonary alveolar proteinosis and their families can be found at:
Some people with PAP go into remission. Others have a decline in lung function (respiratory failure) that gets worse, and they may need a lung transplant.
Call your provider if you develop serious breathing symptoms. Shortness of breath that gets worse over time may signal that your condition is developing into a medical emergency.
Levine SM. Alveolar filling disorders. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 85.
Trapnell BC, Mccarthy C. Pulmonary alveolar proteinosis syndrome. In: Broaddus VC, Ernst JD, King TE, et al, eds. Murray and Nadel's Textbook of Respiratory Medicine. 7th ed. Philadelphia, PA: Elsevier; 2022:chap 98.