Hypersomnia as the first presentation in a patient with insulinoma: A case report and review of the literature.

Insulinoma is a rare neuroendocrine tumor. Hypersomnia as the first presentation in a patient with insulinoma is even more rare and may be easy to misdiagnose. We are herein reporting a case of insulinoma initially presenting with prolonged sleep time and extreme difficulty in waking. The abovementioned symptoms occurred every 2-3 months. Over the last 2 months, the attacks had become more frequent and severe. On computed tomography examination, a 12×9-mm cystic nodule was detected in the uncinate process of the pancreas, which was pathologically diagnosed as insulinoma. Since resection, the symptom of hypersomnia has not occurred again. The aim of the present report was to raise awareness among physicians to consider insulinoma in the differential diagnosis of hypersomnia in patients without other known diseases.