A duodenal ampullary tumor with malignant transformation of papillary polyps: a case report and literature review.

Periampullary carcinoma refers to a malignant tumor within 2 cm of the duodenal ampulla. Primary ampullary carcinoma is very rare, accounting for only 0.2% of malignant gastrointestinal tumors. The small intestine accounts for 75% of the length of the gastrointestinal tract, and primary tumors in the small intestine account for only 2% of all gastrointestinal tumors. Here, we report the case of a duodenal ampullary tumor with malignant transformation of parapapillary polyps. The patient had both a primary ampullary tumor and high-grade intraepithelial neoplasia of juxtapapillary adenomatous duodenal polyps.