Abstract
A 24-year-old man was admitted to our hospital because of unconsciousness and very low blood glucose. Computed tomography (CT) and magnetic resonance imaging (MRI) showed a large tumor (11cm) with solid component in the tail of the pancreas. The patient was diagnosed with insulinoma of the pancreatic tail, and laparoscopic distal pancreatectomy was performed. Immunohistochemical examination was positive for insulin and a part was positive for glucagon. The post-operative course was uneventful, and the patient is alive without recurrence at three years and two months.