Pulmonary alveolar proteinosis is a rare disorder that causes the air sacs in your lungs to become clogged with a natural substance called surfactant.
Causes of Pulmonary Alveolar Proteinosis
You have millions of air sacs (alveoli) in your lungs. These air sacs move oxygen into your blood. Alveolar walls contain surfactant. This is a substance made of fats, proteins, and other substances. This surfactant helps the alveolar walls stay open to allow air to move in and out. Cells called alveolar macrophages help clear the surfactant and stop it from building up.
In most cases of pulmonary alveolar proteinosis in adults, the cause is thought to be a problem with granulocyte-macrophage colony-stimulating factor (GM-CSF). This substance is needed to make the alveolar macrophages function properly and maintain the right amount of surfactant.
Types of Pulmonary Alveolar Proteinosis
This condition is sometimes called phospholipidosis or pulmonary alveolar lipoproteinosis.
There are three types of pulmonary alveolar proteinosis:
- Autoimmune pulmonary alveolar proteinosis. This is the most common type.
- Secondary pulmonary alveolar proteinosis. This is due to exposure to a toxin or another medical condition.
- Congenital pulmonary alveolar proteinosis. This type happens because of genetic defects.
Autoimmune pulmonary alveolar proteinosis affects about 7 of every 1 million people. It typically affects adults aged 30 to 40 years, but children can get it as well.
This disease affects two to three times more men than it does women. About 70% of those with the disease are smokers.
Symptoms of Pulmonary Alveolar Proteinosis
Some people with pulmonary alveolar proteinosis may not have any symptoms. For others, the symptoms include:
- Shortness of breath ( dyspnea)
- Cough
- Fever
- Chest pain
- Weight loss
- Abnormal growth of your fingernails and toenails (clubbing)
- Low levels of blood oxygen
Diagnosis of Pulmonary Alveolar Proteinosis
Your doctor will take a detailed medical history and do a physical exam. Your doctor might be able to hear crackles when they use a stethoscope to listen to your lungs.
Some of the tests that may be needed are:
- A computed tomography (CT) scan of your chest or a chest x-ray
- A bronchoscopy to get a sample of fluid or lung tissue
- Surgery to get a sample of lung tissue ( biopsy)
- Blood tests to find out what type of pulmonary alveolar proteinosis you have
Treatment for Pulmonary Alveolar Proteinosis
Of those with autoimmune pulmonary alveolar proteinosis, about one-third don’t have symptoms, and 5% to 7% improve without any treatment.
But if you have severe pulmonary alveolar proteinosis, it’s important to get treatment. This disease is fatal within five years for about 20% of people. The most common cause of death is respiratory failure, which is what happens when you aren’t getting enough oxygen in your blood.
Lung washing. The fluid in the alveoli can be washed out with a salt solution (saline). This is known as a lung lavage. A special tube is inserted through your mouth or windpipe into one lung. If your symptoms are severe, your entire lung may need to be washed. This is done under general anesthesia. The other lung is washed a few days later.
For some people, whole-lung lavage is needed only once. For others, it might be needed every six months or every year.
Researchers found that 82% of those with pulmonary alveolar proteinosis showed improvement after a whole-lung lavage. There were also no serious complications.
Removing toxins. If you have secondary pulmonary alveolar proteinosis, the underlying cause will need to be treated. For example, if it’s due to a toxin, the toxin will have to be removed and avoided.
Stimulating the immune system. A substance that stimulates your body to produce white blood cells may be given by injection or inhaled. This substance is called recombinant granulocyte-macrophage colony-stimulating factor (GM-CSF).
Some studies have shown that this substance is effective in treating autoimmune pulmonary alveolar proteinosis. But it’s generally not useful for those with secondary or congenital pulmonary alveolar proteinosis.
Bronchodilator. If you have symptoms of asthma, your doctor may prescribe medication to improve your airflow (bronchodilator).
Lung transplant. In rare cases, a lung transplant may be needed. But the disease may still return in transplanted lungs. A lung transplant is recommended only if all the other treatments haven’t worked.
Newer treatments. Some of the newer therapies being studied include:
- Rituximab kills the cells that produce the granulocyte-macrophage colony-stimulating factor autoantibodies. These are the antibodies that stop it from stimulating the alveolar macrophages. But more studies are needed.
- Some doctors have used a procedure to physically remove the granulocyte-macrophage colony-stimulating factor autoantibodies from the blood (plasmapheresis).
