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: Medicine
[{'content': "Diffuse hyperpigmentation is seen in all except: September 2007 \nSelect and explain. \nA. Addison's disease, B. Cushings syndrome, C. Porphyria cutanea tarda, D. Phenylketonuria", 'role': 'user'}, {'content': "Answer: D \nExplanation: Ans. D: Phenylketonuria Common causes of diffuse hyperpigmentation: Addison's disease Porphyria cutanea tarda Cushing's syndrome Hemochromatosis Phaeochromocytoma Biliary cirrhosis High dose ACTH therapy Phenylketonuria results in hypopigmentation", 'role': 'assistant'}]