Pulmonary alveolar proteinosis (PAP) is a rare lung disease that results when the surfactant which coats the alveoli, also called the air sacs, in the lungs builds up and prevents oxygen from passing through into the blood.  This can make breathing difficult.

Key Facts

  • PAP is a rare disease which occurs in approximately seven people per million.
  • Autoimmune pulmonary alveolar proteinosis or aPAP accounts for 90% of PAP diagnosis.
  • Symptoms of PAP are similar to other lung diseases, such as shortness of breath and cough, which can delay getting the correct diagnosis.
  • A simple blood test can help with a quicker diagnosis.
iframe video

Living with aPAP: Karli's long road to diagnosis

Watch Video

I was at the beach, and it took me thirty minutes to get from the hotel room down to the beach. And I couldn't walk the fifty feet to go from the pier to my beach chair, and I just knew something was wrong. Somebody’s got to be able to help me. The first thing I was diagnosed with was bronchitis and I was treated with the normal antibiotics and steroids for a couple of weeks and when I didn't get better, I went back and they thought maybe you have asthma. So, they treated me for asthma. I saw nine different kinds of specialists and I finally found my pulmonologist that did diagnose me with aPAP. When I first saw my pulmonologist and I told him what had been going on, I told him that I couldn't keep living like this, which is not something I had told any doctor before that, and he actually took me seriously. He sent me immediately that day in his office to have pulmonary function testing and he sent me for x-rays. And as soon as they came back, he came back in the room and he was like “I don’t know you walked in here from the parking lot”, because my lung function was 43% - which is crazy that I was just walking around like that. He was like “I don’t really know how you’re still standing but a lot of things make sense and we’re going to get to the bottom of it.” I found out that there was a blood test to confirm aPAP after I was already diagnosed. A quicker diagnosis would have meant that I didn't miss out on three years of my life. For people that are living with unresolved respiratory symptoms, I’d say don't give up on yourself and advocate for yourself. Lung disease gets dismissed as all kinds of things. For me it was dismissed as anxiety, GI issues. If things are not adding up just keep looking for an answer. When you can't breathe, nothing else matters.

Could it be aPAP?

If you were diagnosed with asthma or pneumonia and your symptoms are not improving with your current treatment, talk to your healthcare provider about aPAP.

graphic of woman coughing

What Causes PAP

There are three primary pathways that result in PAP. They all result in the inability to clear the surfactant within the alveoli which causes a buildup of protein in the air sacs that makes oxygen exchange more difficult.

  • Autoimmune (aPAP) – This is the most common form of PAP.   It was previously called idiopathic PAP.   This type of PAP occurs because of the production of antibodies (anti-GM-CSF antibodies) that stop the macrophages (specialized cells) from doing their job of removing the extra surfactants from the lungs’ air sacs.
  • Congenital – This is the least common type of PAP and is the result of a genetic mutation which occurs at birth.
  • Secondary – This type of PAP is caused by another disease, such as myelodysplastic syndrome or chronic myelogenous leukemia, certain infections, and has also been linked to the inhalation of harmful toxins such as silica and talc.

How PAP Affects Your Body

PAP results in an inability of oxygen to be passed through your bloodstream to get to all the cells in your body which can lead to low blood oxygen levels and cause shortness of breath.  PAP may also result in:

  • Respiratory failure that may become life-threatening
  • Increased risk for infections

Who Is at Increased Risk for PAP?

  • People who use tobacco products 
  • Occupational exposure (more commonly associated with secondary PAP) 
    • Stone cutters/quarry workers and others with silica exposure
    • Indium-exposed workers (such as those who work to manufacture liquid crystal displays (LCDs), touch screens, and solar cells).   
  • People with family members who also have PAP

Page last updated: June 25, 2025

Freedom From Smoking Clinic - Huntingdon, PA
Huntingdon, PA | May 07, 2025
Freedom From Smoking Clinic - Lebanon, PA
Lebanon, PA | May 14, 2025