What is nonspecific interstitial pneumonia (NSIP)?

Nonspecific interstitial pneumonia (NSIP) is a rare disorder that affects the tissue that surrounds and separates the tiny air sacs of the lungs. These air sacs, called the alveoli, are where the exchange of oxygen and carbon dioxide takes place between the lungs and the bloodstream.

With interstitial pneumonia the mesh-like walls of the alveoli become inflamed. The pleura (a thin covering that protects and cushions the lungs and the individual lobes of the lungs) might become inflamed as well. Over time, this inflammation can lead to permanent scarring of the lungs.

NSIP can be found in a number of different diseases, including connective tissue disorders (diseases that affect the structural tissues in the body), reactions to certain medications, HIV, as well as other conditions. Some patients also have idiopathic NSIP, which means that the specific cause of the lung disease is unknown.

What are the forms of nonspecific interstitial pneumonia (NSIP)?

There are two primary forms of NSIP — cellular and fibrotic. The cellular form is defined mainly by inflammation of the cells of the interstitium. The fibrotic form is defined by thickening and scarring of lung tissue.

This scarring is known as fibrosis and is irreversible. When the lung tissue thickens or becomes scarred, it does not function as effectively. Breathing becomes less efficient, and can lead to lower levels of oxygen in the blood.

Both inflammation and fibrosis may be present at the same time. Generally, the prognosis is better for patients with the cellular form of NSIP as inflammation is often reversible but fibrosis is permanent.

How common is nonspecific interstitial pneumonia (NSIP)?

Nonspecific interstitial pneumonia has only been defined for a relatively short time, and less is known about how common it is versus other kinds of interstitial pneumonia. Caucasians appear to account for most of the cases, with an average age of onset between 40 and 50 years. There does not seem to be a correlation between cigarette smoking and NSIP.

What are the symptoms of nonspecific interstitial pneumonia (NSIP)?

A person with nonspecific interstitial pneumonia may have these symptoms:

  • A dry cough.
  • Shortness of breath, which may occur after effort or become worse over time.
  • Difficult or labored breathing.
  • Fatigue.
  • Clubbing, or enlargement of the fingertips at the base of the nails. Clubbing may be present due to a lack of oxygen in the blood. Generally, this occurs in only about 10% of people with NSIP.

What causes nonspecific interstitial pneumonia (NSIP)?

No one is really sure what causes nonspecific interstitial pneumonia. Many researchers believe that it is an autoimmune disease, because of the similarities between NSIP and certain connective tissue diseases, such as systemic sclerosis. Some researchers suggest that genes are involved, with heredity playing a role in its development. Inhaling chemicals or dust, use of certain chemotherapy drugs, or radiation treatment could result in the lung damage associated with NSIP.

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