Diagnostic work-up and surgical management of insulinoma: A retrospective analysis from a tertiary referral center

Insulinoma is a multifaceted disease that poses several challenges in terms of clinical presentation, diagnostic work-up, and surgical management. The aim of this study was to describe diagnostic work-up, surgical management, and postoperative outcomes of patients with insulinoma. All consecutive patients who underwent surgery for insulinoma at San Raffaele Hospital (Milan, Italy) between January 2008 and January 2022 were included. Overall, 98 patients were considered. The median delay between presenting symptoms and insulinoma diagnosis was 10 months (IQR, 4–21). Insulinoma diagnosis was made at our Institution in 45 patients, 20 of whom referred within 6 months from symptoms onset. In this subgroup, the median interval between symptoms presentation and insulinoma diagnosis was 4 months (IQR, 2–6), as compared to 14 months (IQR, 10–26) in patients (n = 25) who referred to our institution after 6 months from symptoms onset (p <.001). The insulinoma was localized preoperatively in all the cases. All patients underwent ≥1 high-quality imaging: computed tomography (CT: n = 87, sensitivity 84%), magnetic resonance imaging (MRI: n = 55, sensitivity 85%) and endoscopic ultrasound (EUS: n = 79, sensitivity 100%). MRI identified the tumor in eight patients with negative CT. EUS localized the insulinoma in three patients with negative CT and negative MRI. Parenchyma-sparing resections were performed in 41 patients. Contact with major vessels, lesion close to Wirsung duct and suspect of malignancy were the main reasons to perform a formal resection. An early referral to high-volume centers is important for reducing diagnostic delay in patients with insulinoma. The diagnostic work-up of insulinoma frequently requires several imaging modalities to be performed, with EUS being the most sensitive one. Parenchyma-sparing surgery for insulinoma should be performed whenever technically and oncologically feasible.