It is most common in young adults between the ages of 20 and 40.
Sarcoidosis is a multisystem disease than can affect a variety of organs in the body.
Many other organs can be involved, in fact, one of its most noticeable symptoms are the peculiar skin lesions, erythema nodusum, that develop on the lower legs. Sarcoidosis is a disease of unknown etiology characterized by granuloma formation in a variety of organs. Granulomas are collections of immune cells and disease that result in the formation of granulomas called granulomatous disorders. There are a variety of granulomatous disorders that closely resemble sarcoidosis, including tuberculosis. The close resemblence to tuberuculosis has led to speculation that sarcoidosis is due to an infectious organism.