This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: CNS Tumors, Subject name: Surgery
[{'content': "A 30 years old male complains of loss of erection; he has low testosterone and high prolactin level in blood; what is the likely diagnosis:- \nSelect and explain. \nA. Pituitary adenoma, B. Testicular failure, C. Craniopharyngioma, D. Cushing's syndrome", 'role': 'user'}, {'content': 'Answer: A \nExplanation: Most common cause of hypersecreting pituitary is Pituitary adenoma. PITUITARY ADENOMA Pituitary adenomas arise primarily from anterior pituitary glandQ Classified as either functional (secreting) or nonfunctional (non-secreting) tumors MC functional tumor is prolactinomaQ, which causes amenorrhea & galactorrhea in womenQ. MRI is IOC for pituitary tumorsQ', 'role': 'assistant'}]