Sarcoidosis is a condition in which inflammatory cells produce nodules called granulomas in multiple organs. Granulomas can develop anywhere in the body, but they commonly affect the lungs, skin, lymph nodes, and eyes. Granulomas change the structure of the tissues around them and, in sufficient numbers, can cause inflammation, damage, and symptoms related to that tissue.
The cause of sarcoidosis is not known. The condition is thought to be associated with both a genetic predisposition and the immune system's reaction to an environmental trigger, such as exposure to a virus, bacteria, allergen, or chemical. Anyone can develop sarcoidosis, but it most frequently occurs in adults of African or Northern European descent who are 20 to 40 years of age. African Americans are the most affected group in the U.S. The Foundation for Sarcoidosis Research states that nearly 2% of the African American population may be affected. Research also suggests a higher rate of disease for women.
Sarcoidosis varies in severity. A person may have the disease without knowing it since mild cases cause few, if any, symptoms and the symptoms may be nonspecific. It can present as an acute illness that resolves on its own within a few years (remission) and may or may not recur. Sarcoidosis can also be a chronic disease that continues over time. According to the National Heart Lung and Blood Institute, more than half of those affected will go into remission within 3 years of diagnosis, and two-thirds will be in remission within 10 years.
Most people with sarcoidosis will not experience long-term health effects, but about one-third will have some degree of organ damage. Sarcoidosis can cause blindness in rare cases and can sometimes be fatal, primarily in those with severe lung or heart involvement.