Glucagonoma

Abstract

Glucagonoma represents about 2 % of the pancreatic neuroendocrine tumors (PanNET). They are accompanied by a diabetico-dermatogenic functional syndrome with typical clinical symptoms due to the raised hormone. The primary tumor is always located in the pancreas, more often in the tail. At diagnosis, the disease is frequently malignant with metastases. CT scan with arterial and venous phases or MRI has a good diagnostic accuracy showing a hypervascularized tumor. Due to the presence of somatostatin receptors, somatostatin receptor scintigraphy is usually positive and can be helpful to confirm the neuroendocrine origin and the staging. Macroscopically, glucagonomas are usually single large tumors, and their diameter is mainly comprised between 3 and 7 cm but can vary in size from 2 to 25 cm. Their histological features are quite the same as those of other well-differentiated PanNET. They express chromogranin, synaptophysin, and glucagon at immunohistochemistry. There are few data on grading in the literature, but no poorly differentiated glucagonomas have been described. The glucagon cell adenomatosis is a recently described neoplastic disease characterized by multiple microadenomas and PanNETs composed of glucagon cells, not related to VHL or MEN1 diseases. Clinically, the patients have elevated serum glucagon levels without any glucagonoma syndrome. As for other PanNETs, the prognosis of glucagonomas depends on several factors such as grade and TNM classification. In the SEER analysis of 1,310 PanNETs, the prognosis of glucagonomas does not differ from all the other PanNET if accorded to the stage