Accurate Preoperative Localization of Insulinomas Avoids the Need for Blind Resection and Reoperation: Analysis of a Single Institution Experience with 17 Surgically Treated Tumors over 19 Years

Presently, the need for and choice of preoperative localization tests for insulinomas remain controversial. We report the results from a single institution experience whereby the management policy adopted was that of accurate preoperative localization before surgical exploration. From 1990 to 2008, 17 patients with a clinical and biochemical diagnosis of an insulinoma who underwent surgery were retrospectively reviewed. The diagnosis of all insulinomas were confirmed pathologically. All tumors were localized preoperatively and an average of 2.2 preoperative localization studies including 1.4 noninvasive studies and 0.8 invasive studies were utilized per patient. Invasive localization modalities were more sensitive (92%) than noninvasive modalities in localizing insulinomas (71%). Intra-arterial calcium stimulation with hepatic venous sampling was the most sensitive invasive modality (100%), whereas magnetic resonance imaging was the most sensitive noninvasive modality (63%). Fifteen of 17 tumors (88%) were localized intraoperatively via inspection/palpation and/or intraoperative ultrasonography. Both insulinomas which were not localized intraoperatively were localized correctly to the distal pancreas via preoperative transhepatic portal venous sampling. None of the patients required a blind resection or surgical reexploration for failed localization. All 17 patients underwent complete surgical resection which included eight enucleations and nine distal pancreatectomies with a cure rate of 94% (16/17) at a median follow-up of 35 (range, 1-217) months. The postoperative morbidity and long-term outcome of enucleation was similar to distal pancreatectomy despite a higher rate of microscopic margin involvement. Accurate preoperative localization of insulinomas is useful as it eliminates the need for blind distal pancreatectomy and avoids reoperation. Complete surgical resection is the treatment of choice, and whenever possible, a pancreas-sparing approach such as enucleation should be adopted.