Endocrine Abstracts

Introduction: Insulinoma is the most common functional pancreatic neuroendocrine tumor (PanNET), accounting for more than 50% of all cases. Diagnosis of insulinomas may be challenging. In this study, we aim to discuss the clinicopathological features and long-term follow-up results of insulinoma cases followed up in our clinic.

Material and Methods: It is a descriptive and retrospective study of 13 insulinoma cases diagnosed over 10 years. All data of the patients were obtained retrospectively from the hospital registry system and patient follow-up files. 72-hour prolonged fasting test was performed as a diagnostic test. CT, MRI, Ga-68 DOTATATE PET/CT, EUS, and selective arterial calcium stimulation methods were used for insulinoma localization.

Results: The mean age of the patients was 53.9±19.7 years, and the mean age at the time of diagnosis was 52.9±18.2 years. There was only one patient diagnosed with MEN-1 syndrome. The mean time from the onset of symptoms to the diagnosis was 15 (7-27.5) months. Symptomatic hypoglycemia occurred in eight patients in the first 6 hours (61.54%) during the test. Symptomatic hypoglycemia develops in only one patient t (7.69%) after the first 24 hours. The median size of lesions identified radiologically by MRI was 15 (12-24) mm, and 46.2% of these lesions were isolated in the pancreatic tail. Multiple lesions in the pancreas were detected in 15.4% of the cases. Invasion into fatty tissues surrounding the pancreas was detected radiologically in 1 patient and pathologically in 2 patients. Only one of these patients had liver metastases as distant organ metastases at the time of diagnosis. According to WHO pancreatic neuroendocrine tumor classification, 5 patients had grade 1, 4 patients had grade 2 and 1 patient had grade 3 disease. Surgery could not be performed because 2 of 13 patients refused to have surgery. Nine patients who underwent surgery were in remission in the postoperative period and no recurrence was observed during the 31±28 month follow-up. Octreotide LAR was started in one of the patients who did not accept surgery.

Conclusion: In recent years, thanks to non-invasive imaging methods that have increased in parallel with technological developments, it has been possible to diagnose insulinoma cases, most of which are smaller than 2 cm, earlier and to treat them appropriately. Our experience also highlights that Ga-68 DOTATATE PET/CT may be useful when cross-sectional imaging fails to localize the pancreatic lesion.