MON-LB055 A Single Center Experience of Multiple Endocrine Neoplasia Type 1 (MEN1) vs Sporadic Insulinoma: What Can We Learn and Where Are We Going?

Background: Further characterization of insulinomas from MEN1 patients versus sporadic cases may help elucidate pathophysiological differences and improve future diagnostic algorithms. Methods A retrospective analysis of all patients with insulinoma were included (MEN1 between 1971-2019; sporadic between 1997-2019). Demographic, clinical, laboratory results including a supervised fast, imaging and intra-arterial calcium stimulation (CaStim) data were retrieved when available. Categorical and continuous variables were compared using Fisher’s exact test and Mann-Whitney U-test, respectively. Results One hundred and thirteen patients were identified with insulinoma (69 women, median 44 years, range 13-78 years); of these, 27 patients had MEN1 (11 women, median 37 years, range 18-64 years). Patients with MEN1-related insulinomas sustained a significantly longer duration of the fast and had larger surgically resected tumors (29.73±15.32 vs 15.4±10.8 hours, p<0.001; and 3.2±1.3 vs 1.6±0.8 cm, p<0.001, respectively). In MEN1 patients, CT and MRI failed to localize a pancreatic neuroendocrine tumor in 3/15 (20%) and 2/11 (18%) of patients. CaStim localized 5/8 (63%) insulinomas in MEN1 patients versus 66/81 (81%) insulinomas in sporadic patients. Conclusion Insulinomas in MEN1 patients are larger and more difficult to localize. The role of insulinoma-specific imaging, including (68)Ga-DOTA-exendin-4 PET/CT, may improve localization sensitivity in MEN1 over CaStim. Unless otherwise noted, all abstracts presented at ENDO are embargoed until the date and time of presentation. For oral presentations, the abstracts are embargoed until the session begins. Abstracts presented at a news conference are embargoed until the date and time of the news conference. The Endocrine Society reserves the right to lift the embargo on specific abstracts that are selected for promotion prior to or during ENDO.