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.
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.
The health care provider will listen to the lungs with a stethoscope and may hear crackles (rales) in the lungs. Often, the physical examination is normal.
The following tests may be done:
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.
These resources can provide more information on PAP:
Some people with PAP go into remission. Others have a decline in lung infection (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.
Reviewed By: Denis Hadjiliadis, MD, MHS, Paul F. Harron, Jr. Associate Professor of Medicine, Pulmonary, Allergy, and Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.