Sarcoidosis is an inflammatory disease that may affect many different parts of the body. Small round spots, called granulomas, form in various organs. The spots hinder normal functioning of those organs.

The lungs are the most commonly affected organs. Granulomas in the lung leave less space for the air exchange that needs to take place. This can cause the lungs to stiffen. Other commonly affected organs are the skin, eyes, liver, and lymph nodes. Rarely, the brain may be affected.

Scientists do not know what causes sarcoidosis. It seems to be related to malfunctioning of the immune system. The disease may possibly be triggered by an infection or exposure to a toxin in the environment.

Some people may be more susceptible to sarcoidosis due to genetic or environmental factors.