A case of malignant insulinoma responsive to somatostatin analogs treatment

Insulinoma is a rare tumour representing 1-2% of all pancreatic neoplasms and it is malignant in only 10% of cases. Locoregional invasion or metastases define malignancy, whereas the dimension (> 2 cm), CK19 status, the tumor staging and grading (Ki67 > 2%), and the age of onset (> 50 years) can be considered elements of suspect.

We describe the case of a 68-year-old man presenting symptoms compatible with hypoglycemia. The symptoms regressed with food intake. These episodes initially occurred during physical activity, later also during fasting. The fasting test was performed and the laboratory results showed endogenous hyperinsulinemia compatible with insulinoma. The patient appeared responsive to somatostatin analogs and so he was treated with short acting octreotide, obtaining a good control of glycemia. Imaging investigations showed the presence of a lesion of the uncinate pancreatic process of about 4 cm with a high sst2 receptor density. The patient underwent exploratory laparotomy and duodenocephalopancreasectomy after one month. The definitive histological examination revealed an insulinoma (T3N1MO, AGCC VII G1) with a low replicative index (Ki67: 2%).

This report describes a case of malignant insulinoma responsive to octreotide analogs administered pre-operatively in order to try to prevent hypoglycemia. The response to octreotide analogs is not predictable and should be initially assessed under strict clinical surveillance.