Health Topics A-Z

What Is Sarcoidosis?

Sarcoidosis is a chronic disease that affects multiple systems in the body. It is characterized by the buildup of immune-system cells in organs. These cells form small groups called granulomas, which lead to inflammation of the involved tissues.

The disease is found throughout the world, in all races and both sexes. Although no one knows why, young women of African descent and people of Scandinavian, German, Irish or Puerto Rican origin are more prone to sarcoidosis. It occurs most commonly between the ages of 20 and 40, although it can occur in children and older adults.

Because the symptoms of sarcoidosis can be vague and can be mistaken for other diseases, it's difficult to estimate how common the disease is. In the United States, an estimated 10 to 40 in 100,000 people have sarcoidosis. Among African Americans, the rate is higher.

Sarcoidosis is not cancer, nor is it contagious. Though it can occur in families, it is not inherited. Usually the disease is not disabling; most people with sarcoidosis live normal lives. In fact, in the majority of cases, the disease appears only briefly and disappears on its own. About 20% to 30% of people with sarcoidosis are left with some permanent lung damage, and in 10% to 15% of patients the disease is chronic. Although not common, death from sarcoidosis can occur if the disease causes serious damage to a vital organ.

What Causes It?

No one knows what causes sarcoidosis. Researchers believe the disease is associated with an abnormal immune-system response, but what triggers this response is not known. In addition, it isn't clear how sarcoidosis spreads from one part of the body to another. Nor do doctors know whether heredity, environment, or lifestyle affects the development, severity, or length of the disease. These are questions that researchers are trying to answer.