derives from/develops from duodenum adenocarcinoma cell duodenal adenocarcinoma cell BTO:0001714 BrendaTissueOBO Malignant neoplasms of the duodenum account for only 0.3-0.4% of tumors of the gastrointestinal tract. 25-45% of malignant neoplasms within the small bowel occur within the duodenum. Duodenal adenocarcinomas are usually located in the periampullary and intraampullary regions; they very rarely involve the duodenal bulb. There is an association of duodenal adenocarcinoma with Gardner's syndrome, Peutz-Jegher's syndrome, celiac disease, and Crohn's disease.