Malignant insulinoma causing liver metastasis 8 years after the initial surgery: report of a case

We report herein a rare case of malignant insulinoma which recurred as multiple liver metastasis 8 years after the initial resection. The patient was a 51-year-old Japanese man who originally presented in 1985 at the age of 43 years suffering from general malaise and syncope. The initial surgery in 1985 involved complete enucleation of a 15 x 13 mm insulinoma located in the uncus of the pancreas. Histopathologically, the tumor was diagnosed as a benign adenoma (insulinoma) which was immunohistochemically stained with only the anti-insulin monoclonal antibody. Macroscopically, there were no signs of either invasion or metastasis. During the subsequent 7 years, he did not show any symptoms or significant abnormality in laboratory data. However, in 1993, the patient again experienced syncope with hypoglycemia and hyperinsulinemia. Ultrasonography revealed multiple echogenic lesions in the liver and a second laparotomy confirmed multiple hepatic metastases from insulinoma, the histopathological findings of which were similar to those of the primary tumor from 8 years before. The patient is currently being treated with streptozotocin and 5-fluorouracil via a catheter in the hepatic artery.