This tumor is located in the majority of cases at the right side of the heart. It may reach size 2-3 times the size of the normal heart. The tumor may appear cystic or pedunculated. Pericardial effusion is always present and results from rupture of cystic areas within the tumor, or from obstruction of cardiac and pericardial lymphatic veins. Cardiac tamponade and hydrops may develop and the outcome is very grave.