AbstractIntroductionSignet ring cell carcinoma (SRCC) of the ampulla of vater is a very rare tumor that is reported infrequently in the literature.Presentation of caseA 59-year-old woman visited our hospital for evaluation of elevated transaminase levels. On laboratory examination of tumor marker levels, carcinoembryonic antigen (CEA) and carbohydrate antigen (CA) 19–9 levels were normal, and DUPAN-2 was elevated. Computed tomography (CT) confirmed a 2cm, enhanced mass in the periampullary region, with marked common bile duct dilatation. Endoscopic retrograde cholangiopancreatography (ERCP) showed a swollen papilla of vater, with a reddish, erosive mucosa. Histological examination of biopsy samples from the ampulla of vater showed signet ri...