What is interstitial lung disease?

Interstitial lung disease (ILD) is another term for pulmonary fibrosis, which means “scarring” and “inflammation” of the interstitium (the tissue that surrounds the lung’s air sacs, blood vessels and airways). This scarring makes the lung tissue stiff, which can make breathing difficult. ILD may be limited to the lung, or it can be related to a condition that may affect other parts of the body, such as rheumatoid arthritis or sarcoidosis.

These illnesses share similar features, including a nonproductive (dry) cough and shortness of breath. Although they may look similar radiographically (on chest X-ray or chest CT scan), ILDs from different causes and conditions have different treatments and outlooks. ILD is more common in adults, but can rarely occur occurs in children.

What causes interstitial lung disease?

There are more than 200 causes of ILD. Because ILD includes many disorders, it is categorized based on the cause. These types of ILD include:

  • ILD related to another health disorder: Some people develop ILD as a result of having an autoimmune disease (the immune system harms the body). Examples of autoimmune diseases include rheumatoid arthritis, scleroderma, polymyositis/dermatomyositis, lupus and sarcoidosis.
  • ILD caused by breathing in harmful substances: People who breathe harmful particles such as coal dust, asbestos, tobacco smoke or hairdressing chemicals may develop ILD.
  • Genetic ILD: A genetic ILD occurs when the disease is passed down among family members. These conditions include neurofibromatosis (a disease in which tumors grow on nerves) and Gaucher disease (marked by enlargement of internal organs, including the spleen and liver, and lesions on the bones).
  • Idiopathic ILD: Idiopathic means the cause is not known. Idiopathic ILD usually affects people over 60 years old.

What are the symptoms of interstitial lung disease?

Most people with ILD have symptoms that make breathing difficult, including:

  • Shortness of breath
  • Coughing, typically nonproductive
  • Decreased exercise tolerance
  • Fatigue
  • Weight loss

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