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 they can cause damage, inflammation and symptoms and may interfere with normal functions.
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, dust, or chemical. Anyone can develop sarcoidosis, but it most frequently occurs in women of African or Northern European descent who are 20 to 50 years of age. It effects about 19 people in every 1,000 in the UK.
Sarcoidosis varies in severity. A person may have the disease without knowing it as mild cases cause no, few, or nonspecific symptoms. It can cause acute illness, resolve on its own within a few years (remission), recur, or continue as a chronic condition. 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.