[Diagnosis of a cardiac mass--a case report].

The authors describe a case of a recidivant pericardial effusion associated to a mass with an unusual, filamentous aspect that involved the upper part of right atrium and surrounded the upper vena cava. Despite the diagnostic techniques employed--transesophageal echocardiography and magnetic resonance imaging, the etiologic diagnosis could not be done, so a biopsy of the mass was made by percutaneous approach using transesophageal echocardiography to control the procedure. The histopathological result was an angiosarcoma of the right atrium. The authors make a brief review of the literature about this rare condition.