[Lofgren syndrome: the relevance of the chest X-ray].

Sarcoidosis is a systemic granulomatosis of unknown origin characterized by a formation of non-caseating granulomas in multiple organs, which can present as a chronic, sub acute or an acute form. Löfgren's syndrome is an acute form of sarcoidosis characterized by the presence of arthritis/arthralgia, eritema nodosum lesions and hilar lymphadenopathy. The authors present 3 case reports of arthritis/ /arthralgia and eritema nodosum lesions in 3 young patients in which the diagnosis was Löfgren's syndrome. The radiological findings were essential for the final diagnosis, especially in the presence of a normal value of serum angiotensin-converting enzyme.