Endocrine Abstracts

Introduction: Insulinoma is a rare neuroendocrine tumor with an incidence of 1 to 4 per million person-years. It is the most frequent endocrine tumor of the pancreas and is revealed by a spontaneous hypoglycemia. This study aimed to determine the clinical characteristics, diagnostic workup, and outcome of patients with insulinoma.

Methods: This is a descriptive, retrospective study including patients with confirmed insulinoma collected over a 32-year period. We collected imaging results, medical treatment, surgical management and histologic findings.

Results: A total of 10 patients were included in this study, with a sex ratio of 1,5. The mean age was 46 ± 15,5 years. Neuroglycopenic and neurogenic symptoms were present respectively in 9 and all cases. The median duration of symptoms was 47 months (3—360). All patients fulfilled Whipple’s triad. On biochemical testing, hypoglycemia occurred at a mean glucose level of 1,8 ± 0,62 mmol/l and at a mean insulin level of 18,9 ± 6,4 mUI/l. The pancreatic lesion was identified on cross-sectional imaging in 6 cases and on endoscopic ultrasound in 3 cases. No lesion was identified in 1 case. The median tumor size was 1,9 ± 1,1 cm. Insulinoma was found in the pancreatic uncinate process in 2 cases; in the pancreas body in 4 cases and in the tail in 2 cases. Multiple insulinoma were found in 1 case and was associated to multiple endocrine neoplasia type 1. Surgical procedures included 2 enucleations and 7 pancreatic resections. Histologic findings concluded to benign endocrine tumors in all cases.

All patients had resolution of symptoms after surgery. The median follow-up is 6 years to date.

Conclusion: The diagnosis of insulinoma can be difficult. The average time between start of symptoms and diagnosis is estimated to be 3 years which is consistent with our case series as well. Our experience also highlighted that in cases where cross-sectional imaging failed to localize the pancreatic lesion, Endoscopic ultrasound could be useful.