This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cushing Syndrome, Subject name: Medicine
[{'content': 'Leading cause of ACTH independent Cushing syndrome is? \nSelect and explain. \nA. Adrenocoical carcinoma, B. Macro-nodular adrenal hyperplasia, C. Micro-nodular adrenal hyperplasia, D. Adrenocoical adenoma', 'role': 'user'}, {'content': 'Answer: D \nExplanation: ACTH independent Cushing Syndrome : constitutes 10% of total cases of Cushing syndrome. The causes of ACTH independent Cushing syndrome: Adrenocoical adenoma (MC) Adrenocoical carcinoma Macro-nodular adrenal hyperplasia (<1%) The most common cause( MCC) of ACTH dependant Cushing syndrome is Pituitary coicotroph adenoma.', 'role': 'assistant'}]