Signet-ring cell carcinoma of the ampulla of Vater: a case diagnosed via repeated biopsies.

Signet-ring cell carcinoma of the ampulla of Vater is a rare tumor. A 74-year-old woman presented with epigastric pain and was diagnosed with cholangitis. Her liver enzyme levels were elevated. Computed tomography showed an enhanced area in the periampullary region and marked common bile duct dilatation. On endoscopic retrograde cholangiopancreatography (ERCP), the ampulla exhibited a normal appearance without ulcer or mass. Histological biopsy confirmed the absence of malignancy. During follow-up, the patient again presented with acute cholangitis multiple times and underwent ERCP each time. The ampulla had the appearance of a reddish and erosive mucosa. Although biopsy was repeated, histological examination did not show any malignancy. After a total of 13 biopsies, the patient was diagnosed with ampullary carcinoma of non-exposed protruded type following the third ERC-guided biopsy. Careful follow-up and frequent endoscopic biopsies are important in cases of papillary carcinoma of non-exposed protruded type with normal ampullary mucosa on initial endoscopy because this condition is challenging to diagnose with a single biopsy.