Diffuse interstitial lung disease refers to a group of lung disorders in which the deep lung tissues become swollen and scarred.

Interstitial lung diseases (ILD) are caused by swelling and scarring of the air sacs (alveoli) and their supporting structures (the interstitium). This leads to reduced levels of oxygen in the blood.

The interstitial lung diseases can be broken down into two large groups:

• Those that have no known cause (idiopathic ILD)
• Those with an identifiable cause

One recent system further divides idiopathic ILD into the following three groups:

• Idiopathic pulmonary fibrosis/usual interstitial pneumonitis (IPF/UIP)
• Nonspecific interstitial pneumonitis (NSIP)
• Acute interstitial pneumonitis (AIP)

There are dozens of different causes of ILD. Many occupational substances can cause ILD, including:

• Asbestos
• Coal dust
• Cotton dust
• Sand (silica) dust

People who are heavily exposed to known causes of occupational lung disease in the workplace are usually routinely screened for lung disease. This can include coal miners, sand-blasters, ship workers, and others.

Occasionally, bird keeping or bathing in hot tubs may cause some forms of ILD.

The following diseases can cause ILD:

• Lupus
• Rheumatoid arthritis
• Sarcoidosis
• Scleroderma

Certain medications (such as bleomycin, amiodarone, and methotrexate) may also cause ILD.

Cigarette smoking may increase the risk of developing some forms of ILD and may cause the disease to be more severe.

• Abnormal enlargement of the base of the fingernails (clubbing)
• Blue color of the lips, skin, or fingernails due to low blood oxygen levels (cyanosis)
• Decreased tolerance for activity
• Dry cough
• Rapid breathing
• Shortness of breath at rest or while active

The health care provider will perform a physical exam. Dry, crackling breath sounds may be heard when listening to the chest with a stethoscope. The health care provider may notice nasal flaring.

The following tests may be done:

• Blood tests to check for connective tissue diseases
• Bronchoscopy with biopsy
• Chest x-ray
• CT scan of the chest
• Lung biopsy
• Measurement of the blood oxygen level at rest or during exertion
• Pulmonary function tests

The treatment depends on the cause of the disease. Most often, anti-inflammatory drugs, such as corticosteroids or immunosuppressing drugs, are prescribed.

If there is no specific treatment for the condition, therapy is aimed at making the person more comfortable and supporting lung function. Those with low blood oxygen levels will receive oxygen. Lung rehabilitation can help people with advanced ILD.

Some patients with advanced ILD may need a lung transplant.

For additional information and resources, see lung disease support group.

Chances of recovery or the disease getting worse depend on the cause, and how severe the disease was when it was first diagnosed.

• Hypoxemia
• Pulmonary hypertension
• Respiratory failure
• Right-sided heart failure (cor pulmonale)

Call your health care provider if you have shortness of breath at rest that lasts for any period of time.

Avoid exposure to substances known to cause lung disease.

Quitting smoking can prevent ILD from getting worse.