malignant pericardial effusion
(muh-LIG-nunt PAYR-ih-KAR-dee-ul eh-FYOO-zhun)
A condition in which cancer causes extra fluid to collect inside the sac around the heart. The extra fluid causes pressure on the heart, which keeps it from pumping blood normally. Lymph vessels may be blocked, which can cause infection. Malignant pericardial effusions are most often caused by lung cancer, breast cancer, melanoma, lymphoma, and leukemia.