Pulmonary Alveolar Proteinosis

Pulmonary alveolar proteinosis (PAP) is a rare lung disease that leads to clogged air sacs (alveoli) in your lungs. It can cause breathing problems, low blood oxygen levels and other problems.


Lungs bronchiole normal alveoli blood capillary and protein surfactant buildup in alveoli with pulmonary alveolar proteinosis
Lung condition called Pulmonary Alveolar Proteinosis (PAP).

What is pulmonary alveolar proteinosis?

Pulmonary alveolar proteinosis (PAP) is a rare lung disease caused by a buildup of proteins, fats and other substances in the air sacs of your lungs (alveoli). It prevents air from getting through the alveoli, so your blood doesn’t get enough oxygen. PAP can make it difficult to breathe.

PAP is a serious lung condition, and getting this diagnosis can be scary. But you can manage the disease and its symptoms with the right treatment. If you have PAP, getting care from an experienced pulmonary medicine doctor (healthcare provider specializing in lung diseases) is important. Your provider can also advise you on healthy lifestyle changes that can improve your quality of life.


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Are there different types of pulmonary alveolar proteinosis?

The different types of PAP include:

  • Autoimmune pulmonary alveolar proteinosis: Autoimmune PAP is the most common form of the disease, affecting about 90% of adults who have it. Your immune system mistakenly attacks cells that help keep your alveoli clear.
  • Secondary pulmonary alveolar proteinosis: Secondary PAP develops when another disease or toxin exposure affects cell function in your alveoli.
  • Congenital pulmonary alveolar proteinosis: Congenital PAP may present from birth, or appear at a variety of ages. It’s the result of changes to certain genes that control how cells in your lungs function. You can inherit the disease from your biological parents.

Who gets pulmonary alveolar proteinosis?

Autoimmune and secondary PAP usually affect people between the ages of 30 and 60. These two types are more common in men or people assigned male at birth (AMAB) than women or people assigned female at birth (AFAB). Smoking and exposure to certain dusts or chemicals increase your risk. Congenital PAP is most common in children under the age of 10, but it may start to appear at any age.

How common is pulmonary alveolar proteinosis?

PAP is rare. It affects between 3 and 40 people per million worldwide.

Symptoms and Causes

What causes pulmonary alveolar proteinosis?

The alveoli have thin walls that allow oxygen to pass from your lungs into your blood. The walls naturally have an oily layer of proteins and fats (called surfactants) that help them stay open so oxygen can pass through. Cells called alveolar macrophages periodically clean the surfactants from the air sacs so they don’t get clogged.

But if you have PAP, the macrophages don’t receive the signal they need to clean your alveolar walls. So surfactants build up and block your alveoli. Oxygen can’t pass through to your blood as it should.


What are the symptoms of pulmonary alveolar proteinosis?

Shortness of breath (dyspnea) is the most common symptom of PAP. Most people with the disease have difficulty breathing while exercising, but some also have breathing problems at rest.

Other symptoms of PAP include:

Can pulmonary alveolar proteinosis be fatal?

PAP can cause life-threatening respiratory failure in severe cases. The disease’s course, however, can range from spontaneous remission to stability, or death due to respiratory failure or secondary infections.

Diagnosis and Tests

How is pulmonary alveolar proteinosis diagnosed?

Your healthcare provider does a physical exam and listens to your lungs if they suspect you have PAP. They’ll also ask questions about your personal and family medical history, as well as your lifestyle. Be sure to tell your provider if you smoke or have had exposure to dust, chemicals or other toxins.

Tests for PAP may include:

  • Blood tests to check your blood oxygen level.
  • A serum biomarker called granulocyte-macrophage colony-stimulating factor (GM-CSF) autoantibody and additional testing to define the cause of PAP.
  • Pulmonary function testing to measure how well your lungs are working.
  • Imaging exams, such as chest X-rays or CT scans.
  • Bronchoscopy, which uses a thin scope to look into your airways.
  • Lung biopsy, which uses bronchoscopy or surgery to remove tissue from your lungs for examination.


Management and Treatment

Lung Washing (Lung Lavage) for Pulmonary Alveolar Proteinosis (PAP).

Is there a cure for pulmonary alveolar proteinosis?

There isn’t a cure for pulmonary alveolar proteinosis at this time.

How is pulmonary alveolar proteinosis treated?

The most common treatment for PAP is whole-lung lavage (WLL), also called “lung washing.” A healthcare provider uses a bronchoscope and saline (sterilized salt water) to clean one lung at a time so you can breathe easier. The procedure takes between four and five hours. You may need the procedure every few months or every year, depending on the severity of your symptoms. Treatment varies depending on the severity of the disease. Some people with PAP won’t need WLL due to the varying course of the disease.

During whole-lung lavage:

  • You receive general anesthesia or sedation.
  • Your healthcare provider inserts a bronchoscope into your mouth and guides it down through your airways into one of your lungs.
  • Your provider delivers oxygen from a machine to your other lung.
  • You wear a vibrating vest around your chest. The vibration loosens the surfactants that are clogging your alveoli.
  • Your provider flushes saline through your lung and suctions it out with the surfactants.
  • They may wash your other lung right away, or they may wait a few days.

Other treatments may include:

  • Bronchodilators: Bronchodilators are medications that relax the muscles around your airways to help you breathe better.
  • Granulocyte-macrophage colony-stimulating factor (GM-CSF) replacement therapy: You inhale GM-CSF through a nebulizer (device that changes a liquid medicine into a mist) or receive it as a shot. The therapy helps the macrophages that clean your alveoli work better.
  • Lung transplant: People with severe PAP and lung damage may eventually need lung transplant surgery. This procedure replaces one or both of your lungs with healthy lungs from a donor.
  • Plasmapheresis and plasma exchange: Plasmapheresis and plasma exchange is a treatment to replace your plasma (liquid part of your blood) with healthy donor plasma. This therapy can prevent your immune system from attacking healthy cells in your alveoli.
  • Supplemental oxygen: Oxygen therapy helps you breathe better. You may receive supplemental oxygen through a face mask or small tubes that go into your nose.
  • Clinical trials: You may consider participating in a clinical trial.


Can I prevent pulmonary alveolar proteinosis?

There are different types of pulmonary alveolar proteinosis. It’s not possible to prevent autoimmune-related or congenital PAP. But avoiding toxins — or wearing a respirator or a well-fitted facemask if you can’t avoid them — may help prevent secondary PAP. Make sure that your facemask covers your mouth and nose.

Outlook / Prognosis

What’s the outlook for someone with pulmonary alveolar proteinosis?

Regular treatments such as whole-lung lavage can help you breathe better and relieve other symptoms. PAP clears up on its own in a small number of people. Without treatment, severe PAP can sometimes cause respiratory failure or death.

Living With

How can I help myself if I have pulmonary alveolar proteinosis?

  • Ask your healthcare provider about clinical trials for PAP treatments.
  • Don’t smoke or breathe secondhand smoke.
  • Follow your healthcare provider’s guidance on getting flu and pneumonia shots.
  • Stay away from people who are sick.
  • Stick to a nutritious diet and manage your weight.
  • Wash your hands after using the toilet and before and after you eat.
  • Work with your provider to build a safe exercise plan.

A note from Cleveland Clinic

Pulmonary alveolar proteinosis (PAP) is a rare lung disease that clogs the air sacs in your lungs. It can cause breathing problems and a range of other symptoms. Several effective therapies manage the effects of PAP. If you have this condition, seek treatment from a multispecialty team of healthcare providers. They can work together to help improve your quality of life.

Medically Reviewed

Last reviewed on 02/22/2023.

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