A glucagonoma is a rare neuroendocrine tumor that originates almost exclusively in the pancreas and probably accounts for 1% of all neuroendocrine tumors. Malignant glucagonomas are islet cell pancreatic tumors that are discovered because of glucagonoma syndrome (in which the glucagonoma autonomously secretes glucagon), because of local mass effects, or incidentally. Glucagonomas originate from the alpha-2 cells of the pancreas. Unregulated production (overproduction) of peptide hormones and growth factors, which are not normally expressed in the tissue of origin, is characteristic of neuroendocrine tumors. Abnormal production of these bioactive peptides can lead to significant systemic toxic consequences and to the promotion of further tumor growth. Although the cause of glucagonoma is unknown, Glucagonoma results from the overproduction of glucagon, a peptide hormone located in the pancreatic alpha cells. Classic symptoms include, but are not limited to, necrolytic migratory erythema (NME), diabetes mellitus, and weight loss.
A glucagonoma belongs to a family of tumours called neuroendocrine tumours (NETs), which are tumours that occur in parts of the body that release hormones in response to stimulation by nerves. A glucagonoma is a tumour in the alpha cells of the pancreas that results in too much of the hormone glucagon being produced. Unfortunately, at the point of diagnosis, the majority (~80%) of glucagonomas have already spread and caused secondary (metastatic) tumours in other parts of the body, most commonly the liver. These are termed malignant glucagonomas.
Glucagonomas do not usually present with clear or specific symptoms because the tumour is known to grow slowly. As the tumour grows, the amount of glucagon released by the tumour will continue to increase.