Pulmonary Alveolar Proteinosis (PAP)


What is pulmonary alveolar proteinosis (PAP)?

PAP is a lung condition that is caused by a build-up of proteins, fats and other substances (collectively called surfactant) in the air sacs of the lungs, called the alveoli. The alveoli are the part of the lungs that contain air. It is there that gases between the lungs and the blood are exchanged.

PAP is a rare disease, affecting about 1 person in 100,000 people worldwide, with fewer than 10,000 of them in the U.S. It generally develops in adults, but it can be congenital (something you are born with). It is sometimes called phospholipidosis or pulmonary alveolar lipoproteinosis.

Are there different types of pulmonary alveolar proteinosis (PAP)?

Yes. Types include:

  • Autoimmune pulmonary alveolar proteinosis (aPAP): This type is the most common and is believed to represent about 90% of adults who get it. These adults are mostly between the ages of 30 and 60 years old.
  • Secondary PAP: This type is a result of having another type of disease or condition or of being exposed to a toxin of some type.
  • Congenital: There is a form of PAP that happens because of genetic defects passed down in families.

Who gets pulmonary alveolar proteinosis (PAP)?

This condition happens more often in men than in women. It usually affects people between the ages of 30 and 60. Exposures like dusts and smoking increase the risk of PAP, which may explain why it has been recognized more often in men.

Symptoms and Causes

What causes pulmonary alveolar proteinosis (PAP)?

In the majority of PAP cases in adults, the cause is suspected to be a lack of or a problem with granulocyte-macrophage colony-stimulating factor (GM-CSF). This substance is needed to make certain immune cells develop. Without it, the air sacs are not able to clear out all traces of protein-containing materials. This leads to accumulation of debris in the air sacs and eventually to breathing problems.

What are the symptoms of pulmonary alveolar proteinosis (PAP)?

PAP has the following symptoms:

  • Shortness of breath, also called dyspnea
  • Chest pain or tightness
  • Fever
  • Weight loss
  • Cough (sometimes, but not always)
  • Low levels of oxygen in the blood
  • Nail clubbing (abnormal growth of toenails or fingernails)

Diagnosis and Tests

How is pulmonary alveolar proteinosis (PAP) diagnosed?

If your doctor suspects PAP, he or she will first examine you. If you have PAP, your doctor might hear a crackling sound when he listens to your lungs. Other tests are likely, including:

  • Blood tests, including those that measure gas levels in your blood.
  • Pulmonary function tests that measure how well your lungs are working.
  • Imaging tests, including chest X-rays or high resolution computed tomography (HRCT) scans.
  • Bronchoscopy, a test that uses a thin scope to look into your airways.
  • Transbronchial biopsy, a less invasive way of using a bronchoscope to test tissue or fluid from the lungs for further testing.
  • Open surgical lung biopsy, a test that removes tissue from the lungs to examine under a microscope.

Management and Treatment

How is pulmonary alveolar proteinosis (PAP) treated?

The mainstay of PAP treatment for a very long time has been therapeutic whole-lung lavage (WLL). This procedure involves cleaning out one lung at a time with saline while the other lung is fed with oxygen. During the procedure, you wear an agitating (vibrating) vest around your chest. As liters of saline flush through your lung through special tubing, the agitation from the vest plus the saline liquid causes your airways to release the breath-clogging surfactant. Another tube positioned in your lung suctions the liquid out of your body. This "lung power-washing" procedure is performed under general anesthesia and usually takes from two to five hours to complete.

Newer therapies being studied include:

  • Granulocyte-macrophage colony-stimulating factor (GM-CSF) given as shots under the skin or inhaled through a nebulizer
  • Rituximab, a monoclonal antibody, given as an intravenous (IV) infusion

If a person has secondary PAP, the underlying cause—such as a tumor—must be treated. If the cause is some type of exposure to a toxin or irritant, the exposure must first be stopped.

A person with PAP may be prescribed oxygen to help with breathing.

A bronchodilator (medication to improve air flow) might be prescribed if your type of PAP causes asthma symptoms.

In a few cases, a person with PAP is treated with a plasmapheresis or a lung transplant. Plasmapheresis removes blood plasma from the body, treats it, and then returns it to the body.

Rarely, someone with PAP will see the condition resolve on its own without treatment.


Can pulmonary alveolar proteinosis (PAP) be prevented?

No. There is no way to prevent this condition from happening at this time.

Outlook / Prognosis

What is the prognosis for someone with pulmonary alveolar proteinosis (PAP)?

Treatment such as whole lung lavage (WLL) can provide relief and return to normal activities within days. Oxygen may be needed for the first few days after the procedure until the lungs finish cleaning and clearing on their own.

Without treatment, PAP can sometimes cause respiratory failure or death.

Living With

How can I help myself if I have pulmonary alveolar proteinosis (PAP)?

  • Do not smoke, and avoid secondhand smoke.
  • Try to stay away from people who are sick.
  • Wash your hands after using the toilet, and before and after you eat.
  • Follow a healthy diet, and seek to achieve and maintain a healthy weight.
  • Get a flu shot every year (Confirm this with your doctor.). You should also have a pneumonia shot.
  • Contact your healthcare provider if your symptoms get worse.
  • You might be eligible to participate in clinical trials. (Ask your doctor about this or visit https://clinicaltrials.gov/)


Are there resources for people with pulmonary alveolar proteinosis (PAP) and their families?

Yes. Among others, you can contact:

Last reviewed by a Cleveland Clinic medical professional on 06/06/2018.


  • Expert knowledge and experience of healthcare providers at Cleveland Clinic
  • Genetic and Rare Disease Information Center. Autoimmune Pulmonary Alveolar Proteinosis. (https://rarediseases.info.nih.gov/diseases/7499/autoimmune-pulmonary-alveolar-proteinosis#diseaseOverviewSection) Accessed 9/23/2020.
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  • National Organization for Rare Disorders. Pulmonary Alveolar Proteinosis. (https://rarediseases.org/rare-diseases/pulmonary-alveolar-proteinosis/) Accessed 9/23/2020.
  • Alshati MH. Alveolar proteinosis: a slow drowning in mud. Cleve Clin J Med. 2014; 81(8):468-470. doi:10.3949/ccjm.81a.13085. Accessed 9/23/2020.
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