What Is Pulmonary Alveolar Proteinosis?

Pulmonary alveolar proteinosis (PAP) is a rare syndrome that affects the lungs. PAP causes protein and fats (surfactant) to build up in the air sacs of the lungs. This buildup prevents air from getting through to the lungs. PAP is a serious but rare condition. It can affect children and adults. PAP can occur in both males and females but is more common in males.

Pulmonary = affects the lungs

Alveolar = tiny air sacs within the lungs

Proteinosis = buildup of protein in tissue

There are three different types of PAP: autoimmune, secondary and congenital.

Pulmonary Alveolar Proteinosis Causes

Causes of PAP vary depending on the type.

Autoimmune PAP is the most common type. This is when your immune system mistakenly attacks cells that remove surfactant from the lungs. Surfactant is a fluid consisting of fat and proteins made in the lungs. Surfactant coats the air sacs in the lungs where oxygen enters the body and helps keep them open, which is essential for life. In a healthy person, the lungs have the right amount of surfactant. If the body cannot clear it properly, the fluid builds up and causes breathing issues.

Secondary PAP occurs with exposure to chemical toxins. Underlying medical conditions, such as certain blood cancers, lung infections and immune issues, can cause secondary PAP as well.

Congenital PAP is caused by mutations (changes) to genes that control how certain lung cells function. It can be present at birth or develop over time.

Pulmonary Alveolar Proteinosis Symptoms

Symptoms of PAP range from mild to severe. Some people may not have any symptoms. The most common symptoms for PAP include:

• Shortness of breath
• Bluish coloring of fingertips
• Dry cough
• Productive cough
• Enlarged lymph nodes
• Weight loss
• Fatigue
• Difficulty breathing

Pulmonary Alveolar Proteinosis Diagnosis

Most people who are diagnosed with PAP visit their doctor because they have breathing troubles. Before testing for PAP, the doctor may rule out other lung conditions, such as pneumonia and bronchitis, with a physical exam. The doctor may suspect PAP based on low levels of oxygen in the blood.

PAP is most often diagnosed through chest X-ray or computed tomography (CT scan). A white pattern linked to PAP can be seen in imaging studies of the lungs. The pattern is called “crazy paving.”

A lung tissue biopsy (a procedure that looks at small amounts of lung tissue under a microscope) may be needed to diagnose PAP. However, a biopsy cannot determine the cause or type of PAP.

Several specialized blood tests are used to diagnose congenital PAP. A pediatric pulmonary specialist will begin treatment once your child is diagnosed with PAP. If your child needs surgery, a pediatric surgeon will be consulted.

Pulmonary Alveolar Proteinosis Treatment

Treatment for PAP depends on the type and severity. Up to 7% of those with PAP see an improvement in symptoms without the need for treatment. The most common treatment option is a whole lung lavage (WLL) procedure. A whole lung lavage cleans the lungs and removes excess surfactant buildup. It makes it easier to breathe. Some people only need to have the procedure once. Others may need it every few months or once a year.

A whole lung lavage is done under general anesthesia. A surgeon flushes one lung at a time with saline (salt water). The other lung is connected to a breathing machine during the procedure. Most people find relief from symptoms with a whole lung lavage procedure.

People with severe cases of PAP that do not respond to whole lung lavage procedures may need a lung transplant. Lung transplants have been successful in infants and children with congenital PAP.

Pulmonary Alveolar Proteinosis Prognosis

The long-term prognosis for PAP is generally very good. There is no cure. Many people with PAP go into remission and do not have symptoms after a whole lung lavage procedure. Those who need multiple whole lung lavage procedures are more likely to decline and have a poor outcome.

People with PAP should not smoke, as it can act as a trigger and cause symptoms to worsen. If your child is diagnosed with PAP it’s important to follow the advice of their health care professional. Their outcome depends on the severity of the disease. In many cases, people who have mild to moderate PAP that does not require a lung transplant can lead a relatively normal life.