Location, incidence, and malignant potential of duodenal gastrinomas.

Duodenal gastrinomas are increasingly found at surgery, yet information about their location and characteristics is based on the results of either pooled series or retrospective reviews of small numbers of selected cases. To address these issues we have analyzed the location, incidence, and malignant potential of duodenal gastrinomas in 65 consecutive patients who underwent removal of all tumor as part of a 10-year prospective study to resect gastrinomas in patients with sporadic Zollinger-Ellison syndrome. The primary gastrinoma was located in the duodenum in 24 patients (37%). There were 19 men and five women aged 32 to 69 years (mean 49.4 years), with symptoms for 0.6 to 35 years (mean 7.9 years). Preoperative studies included serum gastrin levels of 114 to 35,798 pg/ml (mean 2060 pg/ml), basal acid output of 7 to 95 mEq/hr (mean 37.6 mEq/hr), and a positive secretin test result in 22 patients. Preoperative imaging studies identified tumor in the duodenal area in 11 patients (46%), but most positive imaging findings were metastatic gastrinoma in lymph nodes, and the primary duodenal tumor itself was identified in only two patients. Portal venous sampling had a localizing gastrin gradient in the inferior or superior pancreaticoduodenal vein in 17 of 23 patients (74%). Each of the 24 patients had a single, small duodenal wall tumor of 2.8 to 10.1 mm diameter (mean 6 mm). Each tumor stained positive for gastrin by immunohistochemistry. Seventeen tumors (71%) were located in the first portion of the duodenum, five (21%) in the second, and two (8%) in the third. Each tumor originated in the submucosa, and 13 (54%) were limited to the submucosa, whereas 11 (46%) were locally invasive, four (16%) extending into the muscularis mucosa and seven (29%) into the muscularis propria. Thirteen patients (54%) had spread to regional lymph nodes, whereas two (8%) had liver metastases. Lymph node metastases were seen with larger duodenal tumors (mean 7.1 vs 5.4 mm; p less than 0.01). The data suggest that a single duodenal wall gastrinoma is a common cause of Zollinger-Ellison syndrome (37%). These small (less than 1 cm) tumors are located in the submucosal layer of the proximal duodenum (92%) and are malignant more often than previously thought (54%).