Insulinoma: Pitfalls in preoperative localization

In patients with biochemical evidence of insulinoma, many techniques have been advocated as the procedures of choice for diagnostic localization without a clear-cut consensus as to their utility. Despite the small size of insulinomas, 90% are solitary and nearly 100% are intrapancreatic. A commonly held belief is that once the diagnosis of autonomous hyperinsulinism is confirmed, it is necessary to secure as much information as possible about the precise location prior to surgery. Although frequently used, preoperative localization studies are expensive, potentially morbid, and worse yet, may be misleading. We present a case study in which the preoperative studies falsely localized the insulinoma to the pancreatic head. Since the introduction of intraoperative ultrasound (IOUS), it is now unusual not to identify and excise the insulinoma in patients undergoing exploration for functioning β-islet cell lesions. Our experience, along with support from the literature, led us to recommend a simplified localization approach, namely IOUS combined with surgical palpation.