<s>[INST] context: Hemorrhagic pericardial effusion most commonly is caused by either tumor or tuberculosis. The most common neoplasm involving the heart is metastatic cancer because primary cardiac neoplasms are rare. The most common primary sites are nearby-lung, breast, and esophagus. The skin lesion in this patient is likely to be a malignant melanoma, which tends to metastasize widely, including to the heart. Most cardiac metastases involve the epicardium/pericardium. (By convention, even though epicardial surfaces are often involved most severely, the term pericardial effusion is typically used when fluid is present, or pericarditis is used when inflammation is present.) A large effusion can cause tamponade, which interferes with cardiac motion. Calcific aortic stenosis leads to left-sided congestive heart failure, with pulmonary edema as a key finding. Coronary atherosclerosis may lead to myocardial infarction, which can be complicated by ventricular rupture and hemopericardium, but the level of troponin I, in this case, suggests that infarction did not occur. Rheumatic heart disease mainly affects the cardiac valves, but acute rheumatic fever can produce fibrinous pericarditis. Tuberculosis is unlikely in this case because no pulmonary lesions were seen on the radiograph. [/INST] question: A 73-year-old woman has had episodes of chest pain during the past week. She is afebrile. Her pulse is 80/min, respirations are 16/min, and blood pressure is 110/70 mm Hg. On auscultation of the chest, heart sounds seem distant, but the lung fields are clear. Neck veins are distended to the angle of the jaw, even while sitting. There is a darkly pigmented, irregular, 1.2-cm skin lesion on the right shoulder. A chest radiograph shows prominent borders on the left and right sides of the heart. Pericardiocentesis yields bloody fluid. Laboratory findings include a serum troponin I level of 0.3 ng/mL. Which of the following lesions is the most likely cause of these findings? | options: A: Calcific aortic stenosis B: Coronary atherosclerosis C: Epicardial metastases D: Mitral valvulitis | answer: C </s>