Sarcoidosis is an inflammatory disease. It starts as tiny, grain-like lumps called granulomas, which most often appear in your lungs or lymph nodes. They can clump together and form larger lumps that attack other organs. Sarcoidosis often affects your skin, eyes or liver.
Sarcoidosis may be mild, or it can be severe and do lasting damage. It does not always cause symptoms, so you can have it without knowing it. Symptoms vary, depending on which organs are affected.
No one is sure what causes sarcoidosis. It affects men and women of all ages and races worldwide. However, it occurs mostly in people ages 20 to 40, African Americans, especially women, and people of Asian, German, Irish, Puerto Rican and Scandinavian origin.
MedlinePlus - Sarcoidosis