An adult case of mixed connective tissue disease associated with perimyocarditis and massive pericardial effusion.

We report the case of a 55-year-old woman with mixed connective tissue disease (MCTD), who developed perimyocarditis associated with massive pericardial effusion. The diagnosis of MCTD was based on clinical and serological findings. We confirmed myocarditis by right ventricular endomyocardial biopsy. The pericardial effusion gradually disappeared after the administration of prednisolone. Although there have been several reports of cardiac disease in adult MCTD, few cases of adult MCTD having perimyocarditis associated with massive pericardial effusion have been reported.