<prompt> All are possible diagnoses in these changes in nails except?Peutz - Jehgers syndromeAddison diseaseCushing diseaseWilson disease  <response>: In patients with Wilsons 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 Addisons disease Cushings disease AIDS Alkaptonuria Ochronosis Irradiation Secondary syphilis Nelson syndrome Dermatological Amyloid primary Basal cell carcinomaBowens disease Lichen planus Malignant melanoma Peutz- Jeghers-Syndrome Porphyria cutanea tarda Radiotherapy and radiodermatitis 