Primary cardiac lymphoma diagnosed by endomyocardial biopsy using transthoracic echocardiography in the substernal window.

We report a case of a 56-year-old man with a cardiac tumor, which grew and spread rapidly in the right heart. Using transthoracic echocardiography (TTE) in the substernal window, a transvenous biopsy of the tumor was performed safely. The tissue diagnosis revealed a diffuse large B cell lymphoma. After undergoing chemotherapy, the tumor was completely cured and the patient continues to be in good health. A biopsy using TTE in the substernal window may be a useful method to diagnose right-sided extensive tumors.