Symptoms of interstitial lung disease vary widely and may persist for months, even years.
Interstitial lung disease (ILD) refers to a group of more than 200 chronic disorders in which lung tissue is damaged, the walls of the air sacs become inflamed, and scarring (fibrosis) begins in the interstitium -- the tissue between the air sacs. Though many of the disorders are uncommon, taken together interstitial lung disease is a frequent cause of respiratory problems, accounting for 15% of all lung disorders evaluated by pulmonologists.
The lung scarring associated with interstitial lung disease leads to stiffness that makes breathing difficult and interferes with the transfer of oxygen in the lungs. The pace of lung deterioration varies greatly from person to person. Interstitial lung disease includes disorders such as pulmonary sarcoidosis, bronchiolitis obliterans organizing pneumonia, asbestosis, and silicosis.
Pulmonary sarcoidosis is an inflammatory disease in which granulomas -- small clusters of cells -- develop in the lungs and adjacent lymph nodes (small, round-shaped groups of immune defense cells that help prevent the spread of infection and protect the bloodstream from viral and bacterial invasion). Pulmonary sarcoidosis can increase lung stiffness, which reduces lung volumes. Bronchiolitis obliterans organizing pneumonia refers to inflammation with blockage of the bronchioles (the small airways in the lungs that branch from the large ones). Asbestosis and silicosis refer to damage caused by exposure to dust from asbestos and silica, respectively. Idiopathic pulmonary fibrosis is a condition of unknown (idiopathic) cause in which progressive scarring of the lungs markedly compromises day-to-day function.
Causes of interstitial lung disease -- A variety of factors can injure the air sacs and result in interstitial lung disease. Possible causes of interstitial lung disease include:
- Certain prescription drugs (including chemotherapy drugs and cardiovascular medications)
- Exposure to environmental toxins
- Infectious agents (such as viruses, bacteria, or fungi)
- Substances that trigger allergic or hypersensitivity reactions (such as certain proteins found in bird droppings) in susceptible persons
- Connective tissue diseases, such as scleroderma, rheumatoid arthritis, and lupus, all of which can cause inflammation and scarring of organs, including the lungs
- The spread of cancer to the lungs from other parts of the body. In many cases, the cause of lung injury is unknown.
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