Surgically Correctable Hyperinsulinemic Hypoglycemia in Adults Insulinoma vs. Nesidioblastosis

ABSTRACT

BACKGROUNDS Hyperinsulinemic hypoglycemia is caused by insulinoma mostly and by nesidioblastosis. While an insulinoma is the most common functional endocrine tumor of pancreas, nesidioblastosis primarily is a childhood disease and is rarely reported in adults. Nesidioblastosis has been defined as a diffuse islet cell hyperplasia accompanied by a differentiation of the islets arising from the pancreatic ductal epithelium. Preoperative localization and proper surgical treatment are crucial because these disases can induce critical and permanent neurologic sequela from the hypoglycemia. However, nesidioblastosis has to be considered differently from the insulinoma in terms of diagnosis and therapeutic aspects in adults. METHODS: We retrospectively analyzed 13 and 3 patients who had been diagnosed as having an insulinoma and nesidioblastosis and who had undergone operations during the 8-year period from 1990 to 1998 at Asan Medical Center. We compared the 2 diseases with respect to diagnosis and therapy. RESULTS: There were 3 men and 10 women with an insulinoma and their mean age was 45 (17~64 years). There were 2 men and 1 woman with nesidioblastosis and their mean age was 45 (22~58 years). The most common clinical manifestation was loss of consciousness, and all the patients had findings compatible with Whipple's triad. The median duration of symptoms before diagnosis was 28 months (6~120 months) in insulinoma and 1.1 months (7 days~2 months) in nesidioblastosis (p=0.009). Hyperinsulinemic hypoglycemia was confirmed during prolonged fasting and the concomitant insulin level was 3~130 U/ml (median=25) in the insulinoma patients and 37~202 U/ml (median=67) in the nesidioblastosis patients (p=0.03). Insulinoma can be localized in 12 patients (93%) preoperatively. The combination of negative angiography and a lack of difference in the insulin concentration gradientin THPVC (transhepatic portal vein catheterization) suggested preoperatively a nesidioblastosis in only one patient (33.3%). All the patients with nesidioblastosis was confirmed intraoperatively by a frozen biopsy. In terms of treating the insulinoma, an enucleation was performed in 5, and pancreatic resection in 8. In nesidioblastosis, subtotal pancreatectomy was done on 2 and pybrus preserving pancreaticoduodenectomy (70%) on one patient. Following the operation, the symtoms of hypoglycemia and the laboratory values were normal in all the patients. CONCLUSION: We observed 13 cases of insulinoma (81%) and 3 of nesidioblastosis (19%). Preoperative suspicion, proper utilization of diagnostic tools, and prudent intraoperative diagnostic procedures enhanced the diagnostic accuracy for hyperinsulinemic hypoglycemia and led to better treatment strategies.