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': 'All are possible diagnoses in these changes in nails except? \nSelect and explain. \nA. Peutz - Jehgers syndrome, B. Addison disease, C. Cushing disease, D. Wilson disease', 'role': 'user'}, {'content': "Answer: D \nExplanation: In patients with Wilson's disease lunula of nail takes on a blue coloration which is called as azure lunula. Excessive fluoride ingestion can turn nails brown or black. Causes of black nails : Systemic Addison's disease Cushing's disease AIDS Alkaptonuria /Ochronosis Irradiation Secondary syphilis Nelson syndrome Dermatological Amyloid (primary) Basal cell carcinoma/Bowen's disease Lichen planus Malignant melanoma Peutz- Jeghers-Syndrome Porphyria cutanea tarda Radiotherapy and radiodermatitis", 'role': 'assistant'}]