This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
[{'content': 'Which is the most common primary malignancy of hea ? \nSelect and explain. \nA. Rabdomyosarcoma, B. Myxoma, C. Fibroma, D. Lymphoma', 'role': 'user'}, {'content': "Answer: B \nExplanation: Myxoma is the most common primary neoplasm of hea (30- 50%). 75% of cardiac myxomas develop in the left atrium. Histologically, it is composed of a myxomatous stroma with large stellate cells mixed with multiWnuleated cells and covered with endothelium. Unusual benign tumors of hea are fibroma, lipoma, angioma, teratoma and cysts. Reference: Schwa'z Principles of Surgery 9e chapter 21.", 'role': 'assistant'}]