Signet ring cell adenocarcinoma of the ampulla of Vater: a rare pathology.

Tumors of the ampulla of Vater are uncommon, representing 0.2% of malignant tumors of the gastrointestinal tract and 8% of malignant tumors of the biliopancreatic area. They arise from the intestinal mucosa of the ampulla of Vater, being adenocarcinoma the most frequent (99% of cases). However, the signet-ring cells subtype at this location is a very rare variant, with only 20 cases reported in the literature (1-9).