We report a unique case of cardiac tamponade in a newborn due to an in
trapericardial lymphangioma. Echocardiography and magnetic resonance i
maging suggested that the mass, which was situated between the right a
trium and the aortic root, was unsuitable for primary resection. A per
icardial window was performed, and over the next 16 months the tumor s
pontaneously regressed.