Sarcoiosis, also called sarcoid (from the Greek 'sark' and 'oid' meaning "flesh-like") or Besnier-Boeck disease, is an immune system disorder characterized by non-caseating granulomas (small inflammatory nodules) that most commonly arises in young adults. The cause of the disease is still unknown. Virtually any organ can be affected; however, granulomas most often appear in the lungs or the lymph nodes. Symptoms can occasionally appear suddenly but usually appear gradually. The clinical course varies and ranges from asymptomatic disease to a debilitating chronic condition that may lead to death.