Yu J, et al. - As malignant insulinoma is extremely rare and accounts for only 10% of total insulinoma cases, researchers performed a retrospective analysis of clinical data from 15 patients with malignant insulinoma treated at Peking Union Medical College Hospital (PUMCH) from 1984 to April 2017. At diagnosis, the patients had median age of 40 (38–54) years. Metastases was noted in more than 50% of the patients at diagnosis, with the liver as the most common metastatic site. Hypoglycemia-related symptoms comprised the main clinical manifestations. Unlike benign insulinoma, the malignant type induces prominent neuroglycopenic symptoms. Concerning the localization examination, 100% positive rates were generated with selective celiac arteriography for both pancreatic primary lesions and liver metastases. Diagnosis of some malignant insulinoma tumors as solitary benigh pancreatic tumors initially, indicates the difficulty to distinguish the two types of tumor clinically. However, metastasis may develop in patients with malignant insulinoma during follow-up visits. This highlights the significance of long-term follow-up visits for patients with insulinoma.