What is pulmonary alveolar proteinosis?

Pulmonary alveolar proteinosis (PAP) is a rare lung condition. It occurs when surfactant builds up in your lungs and clogs your air sacs, or alveoli. Surfactant is a natural substance that lowers surface tension in your lungs and allows you to breathe. The three main types of PAP are congenital, acquired, and secondary.

PAP causes mild to severe breathing problems, ranging from shortness of breath with a lot of exertion to shortness of breath at rest. It can be fatal if you don’t get treatment for a severe case of it.

It’s possible to have PAP without having any symptoms. The symptoms of PAP include:

  • difficulty breathing, which is the most common symptom
  • coughing, occasionally with mucus or blood
  • a blue-tinged facial color
  • general fatigue
  • a low-grade fever
  • weight loss

The symptoms of PAP can progress to severe lung impairment and respiratory failure if you don’t get treatment for them.

Surfactant coats your lungs. PAP develops when this substance reaches an abnormal level and blocks your lung’s airways. This impairs the transfer of oxygen from your lungs to your blood. It often results in labored breathing. The exact cause of PAP is unknown.

According to the PAP Foundation, this condition affects roughly 3.7 people per million. This makes it a rare disease. The majority of cases appear later in life. People between the ages of 30 and 50 are more likely to develop the condition, and men are at greater risk than women.

Cases of PAP may be linked to:

  • an immune response that blocks the breakdown of surfactant
  • lung infection or pneumonia
  • certain cancers
  • exposure to toxic particles in the environment or workplace, such as silica or aluminum dust

If your doctor suspects you have PAP, they may perform the following tests:

  • a chest X-ray to look for white patches in your lungs
  • a CT scan of your chest to look for white patches in your lungs
  • blood tests to check for antibodies that are related to PAP
  • pulmonary function tests to check the air capacity of your lungs
  • a bronchoscopy with saline wash to obtain a fluid sample from your lungs
  • a lung biopsy to examine a tissue sample from your lungs

In some cases, the symptoms of PAP are so mild that no treatment is necessary. The condition sometimes resolves without treatment. If you have certain mild symptoms, supplemental oxygen therapy may be enough to treat the condition.

If you have severe symptoms, your doctor can wash the surfactant out of your lungs with a saline solution. Depending on the area affected, they may wash only part of your lung. If your entire lung needs to be cleaned, they’ll use a procedure called “whole lung lavage.” In this procedure, they’ll fill one of your lungs with saline solution and drain it, while keeping your other lung ventilated.

One wash may be enough to clear your symptoms, but you’ll most likely need multiple treatments. Your doctor may also prescribe a blood-stimulating medication, which is a newer treatment that has improved symptoms for some people. As a last resort, they may recommend a lung transplant.

It’s important to get treatment for PAP if your condition is severe. PAP is fatal within five years of diagnosis for about 20 percent of people with the condition. The cause of death is usually respiratory failure or lack of oxygen in the blood.

For other people, PAP is manageable with treatment. You can live a relatively normal life after your doctor diagnoses you with PAP and treats it. However, you may have still have some shortness of breath for years afterward. You may have permanent scarring in your lungs and reduced lung capacity, but this is uncommon. All people who develop PAP have an increased risk of pneumonia, which is an infection in the lung.