Surgical removal of the tumour is the therapy of choice in insulinomas and is considered curative in benign insulinomas. Optimal preoperative localization of the lesion is warranted in order to reduce the morbidity by helping to optimize the surgical procedure. The successful preoperative localization of insulinomas is a challenging problem since approximately 30% of insulinomas cannot be visualised using CT and/or MRI.

Palpation and intraoperative ultrasound will allow identifying the lesion in approximately 70-80% of cases. However, it remains a challenge to find small or multiple tumours in the pancreas and partial pancreatectomy is frequently required, especially if the lesion is located close to the pancreatic duct. If no insulinoma can be identified pre- or perioperatively, the diagnosis of nesidioblastosis may be established by resection and histopathologic evaluation of the pancreatic tail. If nesidioblastosis is present, partial pancreatectomy is required; the challenge is to remove enough tissue in order to avoid hypoglycaemia while keeping enough functional endocrine pancreatic tissue so that the patient does not become diabetic.

Currently, the risk of reoperation is considered lower than the risk of diabetes; surgeons therefore choose a more conservative approach as compared to diffuse CHI where hypoglycaemias are more life-threatening.