Pulmonary Alveolar Proteinosis
Most commonly referred to as PAP, pulmonary alveolar proteinosis is a rare lung condition that occurs when protein buildup in the lungs clogs your air sacs (alveoli). It causes mild to severe breathing problems and can be fatal if left untreated.
A milky substance called surfactant coats your lungs. PAP develops when this substance reaches an abnormal level and blocks the lung’s airways. This prevents the oxygen in your blood from going where it’s needed and results in labored breathing.
According to the PAP Foundation, PAP affects roughly 3.7 people per million, making it a rare disease (PAP Foundation). While it can occur at birth (extremely rare), the vast 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.
While the exact cause remains a mystery, studies have shown a link to:
- immune response that blocks the breakdown of surfactant
- lung infection or pneumonia
- certain cancers
- exposure to toxic dust such as silica or aluminum dust.
Some people have no symptoms at all, but most experience:
- difficulty breathing
- coughing (occasionally with mucus or blood)
- general fatigue
- low fever
- weight loss
- blue facial tinge
The symptoms can progress to severe lung impairment and respiratory failure if left untreated.
After hearing your symptoms, your doctor may perform the following tests:
- chest X-ray to check for white patches in the lungs associated with PAP
- computed tomography (CT) scan of the chest to check for white patches associated with PAP
- pulmonary function tests to check air capacity in the lungs
- bronchoscopy with saline wash to obtain fluid sample
- lung biopsy to get a tissue sample for pathology examination
The condition sometimes resolves completely on its own. Other times, the symptoms are so mild that no treatment is needed.
If you have severe symptoms, the surfactant can be washed out of your lungs with a saline solution. Depending on the area affected, your doctor may wash only part of your lung. If your entire lung needs to be cleaned, then a procedure called whole lung lavage will be performed. A whole lung lavage involves filling one lung with solution then draining, while the other lung is kept ventilated.
One wash may clear you of symptoms, but you’ll most likely need multiple treatments.
You may opt for a blood-stimulating medication, a newer treatment that has improved symptoms for some patients.
As a last resort and depending on your specific circumstances, your doctor may recommend a lung transplant.
Tragically, up to 25 percent of patients die within five years of diagnosis, usually of respiratory failure (lack of oxygen in the blood).
For others, PAP can be managed with treatment, and you can live a relatively normal life. However, you may have shortness of breath for years after, and more rarely, you may have permanent scarring in the lungs and reduced lung capacity. All PAP sufferers have an increased risk for pneumonia.
Written by: Annette Ha
Updated on Feb 15, 2013
Medically reviewed by Brenda B. Spriggs, MD, MPH, FACP