Sarcoidosis.

Sarcoidosis is a multisystem granulomatous disorder of unknown aetiology. The condition commonly affects young adults and frequently presents with bilateral hilar lymphadenopathy with or without pulmonary infiltration, ocular or cutaneous lesions. The clinical presentation can be extremely varied depending upon the organs affected. The diagnosis is firmly established when recognised clinical and radiographic findings are supported by histological evidence of discrete non-necrotising epithelioid cell granulomata in one or more organs. Sarcoidosis is usually self-limiting with spontaneous resolution, although in a few patients there is a progressive downhill course, culminating in irreversible fibrosis and severe impairment of organ function.