[The diagnosis and treatment of insulinoma and gastrinoma]

The gastroenteropancreatic endocrine tumor is relatively rare tumor that originate from pancreas, duodenum, and a variety of neuroendocrine cells. The differential diagnosis and preoperative localization of the tumor are important, because surgical resection of the tumor is the first choice of treatment. Of these tumors, insulinomas and gastrinomas are usually small in size (less than 2.0 cm), and methods of preoperative localization such as ultrasonography, computed tomography or magnetic resonance imaging often fail to identify them. These tumors often malignant, and tumors as small as 1 to 2 mm might develop lymph node metastases especially in gastrinomas. Recent studies have shown that selective arterial calcium stimulation test and hepatic venous sampling using intraarterial calcium injection as the insulin secretagogue are useful for detection of small insulinomas, and the selective intraarterial injection of secretin test combined with venous sampling (Imamura technique), for detection of small gastrinomas. In addition, somatostatin-receptor scintigraphy is widely used in Western countries. Moreover, detection of the tumor during operation using ultrasonography delivered much better results than preoperative diagnoses. These tumors may be associated with multiple endocrine neoplasia type 1, and MEN1 gene mutation analysis is necessary in those patients.