[Acute mediastinitis in rheumatoid arthritis)]

During an exacerbation of rheumatoid arthritis in a 54 year old woman, an acute lifethreatening complication developed with pleuro-mediastino-pericarditis presenting as a superior vena cava obstruction-like syndrome. This was later associated with thrombosis of the left external jugular vein and a peripheral Horner's syndrome. She did also develop arterial hypertension with retinopathy and severe cardiac failure. Treatment with antirheumatic drugs and penicillin resulted in gradual improvement over the course of several months. The affected visceral organs were not permanently damaged. Knowledge of the clinical features of this condition is important, since a cure even with conservative treatment is possible.