These arise from the endocrine cells, and make up about 1% of all pancreatic tumours. Endocrine cells may develop generalized hyperplasia (all the islets get bigger), adenoma (a single benign tumour), multiple adenomas, and carcinoma (a malignant tumour). Occasionally endocrine tumours may develop as part of the hereditary Multiple Endocrine Neoplasia (MEN) Syndrome, of which there are two types.
The hormones that these tumours produce can give rise to typical conditions, e.g.
- Insulinoma (excess insulin)
- Gastrinoma (excess gastrin)
- Watery diarrhea (excess VIP or vasoactive intestinal polypeptide)
- Somatostatinoma (excess somatostatin)
- Glucagonoma (excess glucagon)
- Carcinoid (excess 5-Hydroxytryptamine)
- PPoma (excess PP or pancreatic polypeptide)
- Bleeding into the gut can sometimes be the first symptom
Of these, insulinoma and gastrinoma are the most common and are therefore described here. The others will not be discussed here.
These tumours are often single and usually benign (i.e. not cancerous). The excess insulin produced by the tumour causes the blood sugar level to become abnormally low from time to time, especially when the patient is hungry. This is called hypoglycaemia, and can cause nervousness, trembling, sweating, slurred speech, incoordination of movements, dizziness, fainting, and fits that may resemble epileptic attacks. Diagnosis is made on the basis of the signs and symptoms of hypoglycaemia, and by proving that the symptoms are accompanied by a low blood sugar level and high insulin level. Once that diagnosis is made, the next step is to find the exact location of the tumour. Scans such as Ultrasound, CT, MR, Endoscopic ultrasound (EUS) and Angiography may be required to achieve this. The ideal treatment is surgical removal of the tumour. In most cases, only the tumour needs to be removed (a procedure called enucleation), though a formal resection of that part of the pancreas may sometimes be necessary, especially if the tumour is adjacent to the main pancreatic duct.
Gastrinomas have a greater chance of turning out to be malignant, and can be multiple. The high level of gastrin produced by the tumour leads to the formation of excess acid in the stomach and a clinical scenario called the Zollinger-Ellison syndrome. It should be suspected if the peptic ulcers develop in a young person or at an unusual site (like the jejunum), sometimes with unexplained diarrhea, concurrent disease of the parathyroid glands, and a family history of gland disorders. Demonstrating a high blood level of gastrin is key to the diagnosis, and scans such as Ultrasound, CT, MR, Endoscopic ultrasound (EUS) and Angiography may be required to find the exact location of the tumour(s). Most of the tumours are found within an area called the Gastrinoma Triangle. Surgical removal of the tumour should be considered if it deemed technically feasible. Failing that, symptoms may be controlled with drugs such as Omeprazole and Octreotide.
For more information on the surgical treatment of these tumours, please look at the page on Pancreas Operations: FAQ (which you can download as an information booklet), and in the Pancreatic Cancer page at What is the treatment of Pancreatic Cancer.