A Case of Sporadic Insulinoma With Unusual Features: Case Report

Abstract: Insulinomas are rare neuroendocrine tumors that usually present with fasting hypoglycemia and require demonstration of Whipple triad and laboratory evidence of hyperinsulinemic hypoglycemia for the diagnosis. The neuroglycopenic symptoms that comprise part of Whipple triad can be very nonspecific. Commonly, there is significant delay in insulinomas being diagnosed, with the symptoms frequently attributed to psychiatric or neurologic disorders. There is considerable variability in the modalities used for preoperative tumor localization, there is no consensus regarding the treatment option of choice, although most authors favor a pancreatic-sparing approach. Our patient did not exhibit the classic neuroglycopenic symptoms at the time of low serum glucose, therefore not fulfilling the criteria of Whipple triad, despite his laboratory and radiologic findings being consistent with an insulinoma. Although vascular invasion and tumor size have been quoted as features denoting more aggressive tumor behavior, our patient's tumor (despite being 60 mm in diameter with vascular space invasion) was classified as a low grade tumor with a low Ki-67 proliferative index of