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: Radiology
[{'content': 'The following is not the differential diagnosis of an anterior mediastinal mass – \nSelect and explain. \nA. Teratoma, B. Neurogenic tumor, C. Thymoma, D. Lymphoma', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Anterior mediastinal masses:-\xa0Thymoma, Lymphoma, teratoma, Aneurysm of ascending aorta, pericardial cyst, retrosternal thyroid, Morgagni hernia.\nMiddle mediastinal masses:-\xa0Lymph node enlargement, bronchogenic cyst, pericardial cyst, Aortic arch aneurysm, coronary / pulmonary aneurysm, azygous vein enlargement.\xa0Tortuous innominate artery(Kant.-II)\nPosterior mediastinal masses:-\xa0Neurogenic tumor (neuroblastoma, schwannoma, neurofibroma), Aneurysm of descending aorta, lymph node enlargement, neuroenteric cyst, anterior meningocele, bochdolek hernia.', 'role': 'assistant'}]