Sarcoidosis (from sarc meaning flesh, -oid, like, and -osis, diseased or abnormal condition), also called sarcoid, Besnier-Boeck disease or Besnier-Boeck-Schaumann disease, is a disease in which abnormal collections of chronic inflammatory cells (granulomas) form as nodules in multiple organs. The cause of sarcoidosis is unknown. Granulomas (of the non-caseating type) most often appear in the lungs or the lymph nodes, but virtually any organ can be affected. Normally the onset is gradual. Sarcoidosis may be asymptomatic or chronic. It commonly improves or clears up spontaneously. More than 2/3 of people with lung sarcoidosis have no symptoms after 9 years. About 50% have relapses. About 10% develop serious disability. Lung scarring or infection may lead to respiratory failure and death. Chronic patients may deal with waxing and waning symptoms over many years.