[Acute miopericarditis as the presenting feature of adult-onset Still's disease].

Adult Still's disease (ASD) was described by George Still in 1896. ASD is a rare inflammatory disorder, of unknown etiology, whose clinical manifestations are manifold. Diagnosis requires high clinical suspicion and exclusion of different etiologies. We report the case of a 20 year old male with fever, arthritis, dyspnea and chest pain. Laboratory findings showed increased levels of cardiac enzymes, and a pleuropericardic effusion was detected in imaging tests, both of them showing myopericarditis. Corticosteroid treatment was started with initial improvement, although the addition of methotrexate was necessary in the following months.