Sarcoidosis with prevalent and severe joint localization: a case report.

Background: Sarcoidosis is a systemic granulomatous disease of unknown origin, characterized by the formation of granulomas without central necrosis. Each organ and tissue can be affected by the disease, but in most cases mainly the lungs and mediastinal lymph nodes but also skin, heart, eyes and joints are involved, the latter are mainly the metacarpophalangeal joints and bone lesions are often associated with involvement of the overlying skin. The diagnosis is often of exclusion, based on clinical and radiological suspicion, and should be confirmed by biopsy, although in each case it is necessary to exclude other possible causes of granulomatosis, including infections by mycobacteria.