Benign congenital intracardiac thyroid and polycystic tumor causing right ventricular outflow tract obstruction and conduction disturbance.

A patient with a rare intracardiac tumor arising from the right side of the interventricular septum who developed conduction disturbances and symptoms of right ventricular outflow tract obstruction is reported. The patient was successfully treated with insertion of a permanent pacemaker and surgical removal of the tumor after two-dimensional echocardiography diagnosed the intracardiac mass. Pathologic examination confirmed the benign nature of the tumor and showed the unusual features of both ectopic thyroid and benign congenital polycystic tumor.