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: Pathology
[{'content': 'The most common mediastinal tumor is- \nSelect and explain. \nA. Neurogenic tumor, B. Pericardial cyst, C. Hernia, D. Teratoma', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Overall most common mediastinal masses\xa0are neurogenic tumors (20%) followed by thymomas (19%), primary cysts (18%), lymphomas (13%) and germ cell tumors (10%).\nMost of the mediastinal masses are located in the anterior mediastinum followed by the posterior (25%) and middle (19%).', 'role': 'assistant'}]