Pulmonary alveolar proteinosis

Pulmonary alveolar proteinosis 

Pulmonary alveolar proteinosis (PAP) is a syndrome, a set of symptoms and signs – not a single disease, in which surfactant in alveoli builds up slowly. This blocks air from entering alveoli and oxygen from passing through into the blood, which results in a feeling of breathlessness (dyspnea).


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.


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


If your doctor suspects PAP, he or she will first examine you. If you have PAP, your doctor might hear a crackling sound when he listens to your lungs. Other tests are likely, including:

  • Blood tests, including those that measure gas levels in your blood.
  • Pulmonary function tests that measure how well your lungs are working.
  • Imaging tests, including chest X-rays or high resolution computed tomography (HRCT) scans.
  • Bronchoscopy, a test that uses a thin scope to look into your airways.
  • Transbronchial biopsy, a less invasive way of using a bronchoscope to test tissue or fluid from the lungs for further testing.
  • Open surgical lung biopsy, a test that removes tissue from the lungs to examine under a microscope.

General Rating Formula for Interstitial Lung Disease (diagnostic codes 6825 through 6833): 

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