The most common location(s) for development of gastrinoma is/are which of the following?

a. Pancreas to the right of the superior mesenteric vein

d. Duodenum

The majority of gastrinomas have been identified to the right of the superior mesenteric vessels within the head of the pancreas or the duodenum. Intraoperative ultrasonography should be available to assist in tumor localization. In addition, intraoperative upper endoscopy may be helpful by allowing transillumination of the duodenal wall and identification of small duodenal gastrinomas. At exploration, any suspicious peripancreatic lymph nodes are excised and submitted for frozen section. Primary tumors located within the substance of the pancreas that are small (< 2 cm) and well encapsulated may be carefully enucleated. Pancreatic tumors without defined capsules or situated deep in the pancreatic parenchyma may require partial pancreatic resection. In the absence of an identifiable pancreatic or duodenal tumor, a longitudinal duodenotomy may be performed at the level of the second portion of the duodenum to allow for eversion of the duodenum in a search for duodenal microgastrinomas. Primary gastrinomas identified within the duodenal wall are resected locally, with primary closure of the duodenal defect.