BACKGROUND:The most common tumors in the ampulla of Vater are adenocarcinomas.Although malignant melanoma usually occurs on the skin,it can also arise in the gastrointestinal and biliary tract.METHOD:We present a case of a 52-year-old,previously healthy man who presented with painless jaundice.RESULTS:Clinical examination revealed dilated intrahepatic and extrahepatic bile ducts and pancreatic duct due to the obstructive mass in the ampulla of Vater.The patient underwent pancreaticoduodenectomy and histopathological diagnosis of the resected tumor mass was malignant melanoma.Thorough clinical examination was preformed,but no other primary or metastatic site of melanoma could be found.In the next few months,the patient developed multiple liver metastases and died.CONCLUSION:An isolated amelanotic lesion in the ampulla of Vater can be a potential diagnostic pitfall,especially in patients who have had melanoma.