Rare Lung Disease

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General Information

Rare Lung Disease Week

Pulmonary alveolar proteinosis (PAP) is a syndrome occurring in ~7 per million people in which surfactant builds up in the tiny air sacs (alveoli) of the lung.

Surfactant is normally present in small amounts and help alveoli stay open. However, in PAP, surfactant builds up and causes shortness of breath and cough and in rare cases, respiratory failure.

The most common type of PAP is autoimmune PAP, an acquired condition caused by antibodies to a protein called GM-CSF which is required for lung cells to prevent surfactant from building up.

Because PAP is so rare, it is often initially misdiagnosed as a more common disease – such as asthma or pneumonia. Only after the failure of several courses of therapy for such diseases is PAP usually diagnosed correctly.

The presence of PAP is suggested by certain symptoms and signs (shortness of breath, low oxygen levels, and "crazy paving" pattern on chest CAT scan which refers to hazy white shadows surrounded by angular lines) and confirmed by examining lung lavage fluid or a lung biopsy specimen. However, lung biopsies are not required for diagnosis and often involve unnecessary invasive procedures. Instead, there is a blood test called the GM-CSF autoantibody that is 100% accurate in diagnosing autoimmune PAP.

Current treatment options include whole lung lavage (WLL) therapy, a procedure performed under general anesthesia in which excess surfactant is washed out of one lung with saline while the other is connected to a ventilator. Inhaled GM-CSF is currently being studied in clinical trials in the U.S. and Europe.

More information about PAP and current research endeavors may be found at www.papfoundation.org

A review of LAM, a cystic lung disease affecting only women, will be provided in a future ATS Lung Disease Week. However further information can be found at www.the lamfoundation.org, one of the most well-established patient foundations for rare lung diseases.   

Lymphangiomatosis is a condition distinct from LAM characterized by the presence of cysts that result from an increase in the size and number of lymphatic channels. These channels are normally present in the body to drain lymph, a fluid that defends the body against infections. The lymphatic system also absorbs fats and vitamins from the intestine and transports them to the blood.

Lymphangiomatosis typically presents at a young age and most commonly affects the lungs and bones. In the lungs, chyle, which is composed of lymph fluid and fats, accumulates in the chest leading to a fluid collection called a chylous effusion. This fluid compresses the lung leading to shortness of breath and cough.

Lymphangiomatosis is often diagnosed when patients present with the combination of bone lesions and chylous effusions. Biopsies are required for diagnosis and show an increase in the size and number of lymphatic channels.

There is no standard treatment or cure for lymphangiomatosis. Symptoms are often managed by procedures that aim to drain the fluid that accumulates in the lung.

Additional information may be found at the Lymphangiomatosis and Gorham's Disease Alliance website - https://www.lgdalliance.org/

Four Facts About Lymphangiomatosis & Gorham's Disease

  1. Lymphangiomatosis, recently classified as generalized lymphatic anomaly (GLA), and Gorham-Stout disease (GSD) are thought to be a spectrum of disease, one aspect of which may affect the lungs and other organs of the thorax. 

  2. Another related complex lymphatic anomaly that has features of GLA and GSD, along with hemorrhagic effusions, called Kaposiform lymphangiomatosis (KLA) was described in 2014.

  3. Pulmonary disease in GLA, GSD, and KLA is often most aggressive in younger patients and is separate and distinct from lymphangiectasia, lymphangioleiomyomatosis (LAM), pulmonary capillary hemangiomatosis, Kaposi's sarcoma, and kaposiform hemangioendothelioma.

  4. GLA, GSD, or KLA affecting the lung may be misdiagnosed as asthma, and can be confused with lymphangiolieomyomatosis (LAM).