An Unusual Presentation of Insulinoma: Confusion With Psychiatric Symptoms

Insulinoma is a rare but common functional neuroendocrine tumor that secretes an excess amount of insulin resulting in mostly fasting hypoglycemia but can also cause postprandial hypoglycemia. It usually presents with neuroglycopenic and autonomic sympathetic symptoms that resolve following the administration of dextrose. The patients may remain symptomatic from 1 week to as long as several decades before diagnosis. Insulinoma presenting with psychiatric symptoms has been documented in case/case series reports. Laboratory findings of elevated insulin and C-peptide level in the presence of hypoglycemia and absence of plasma sulfonylurea are suggestive of the diagnosis. Localization of the tumor is essential preoperatively. Surgery usually cures most of the patients, but a minority will have a recurrence especially with malignant insulinoma. The manuscript presents a case of insulinoma presenting with psychiatric symptoms without sympathetic symptoms that led to the delay of the diagnosis for 3 months as initially thought to be related to psychiatric problems. Pancreatic insulinoma was localized by computed tomography (CT) scan and confirmed with endoscopic ultrasound (EUS). The patient underwent successful resection of the tumor, and her symptoms were completely resolved.