A suspected insulinoma with the unexpected histopathological finding of a nesidioblastosis – A case report and literature review

Abstract

Introduction: Nesidioblastosis is a hyperplasia of the beta cells that causes persistent hyperinsulinemic hypoglycemia, unfortunately, it is difficult to diagnose through imaging studies. Case presentation: A 68-year-old woman with palpitations, diaphoresis, dizziness and alterations in the level of consciousness that improve with food intake. Laboratories: glucose 35.0 mg/dl, insulin 12.5 mUI/ml, proinsulin 14.1 pmol/L and peptide C 2.55 ng/ml. Octreoscan reveals an abnormal epigastric uptake area and the tomography shows a focal hypervascular lesion in pancreatic body of 12×11 mm. A distal pancreatectomy was performed without palpating the tumor in transoperative period, and a diffuse nesiodioblastosis was reported in the histopathological study. The patient persists with hypoglycemia and an additional pancreatic resection was performed, resecting 90% of the organ. Although an insulinoma was not located in the piece, an area surrounded by connective tissue was observed where islet hyperplasia was more accentuated. Discussion: The pathophysiology of nesidioblastosis is unknown, its main differential diagnosis is insulinoma and this should be suspected when the tumor can not be identified. Most agree that a pancreatectomy that involves 60-80% of the total organ can control glucose levels with low risk of diabetes and pancreatic insufficiency. Conclusion: The nesidioblastosis should be suspected when a hyperinsulinemic hypoglycemia is difficult to control and when a tumor can not be identified. The extension of the pancreatectomy should be individualized and if an insulinoma is not localized and a nesidioblastosis is suspected, an intraoperative histopathological examination with frozen section evaluation for the margins could determine the extent of pancreatectomy.