In this article. Sarcoidosis is an inflammatory disease that affects multiple organs in the body, but mostly the lungs and lymph glands. In people with sarcoidosis, abnormal masses or nodules (called granulomas) consisting of inflamed tissues form in certain organs of the body.he exact cause of sarcoidosis is not known. It is a type of autoimmune disease associated with an abnormal immune response, but what triggers this response is uncertain. How sarcoidosis spreads from one part of the body to another is still being studied.