Pancreatic neuroendocrine tumours
- Lesion
Rare pancreas tumours of hormone cells. Some make one hormone in excess and cause a striking syndrome; many make none and grow silently.
What it is
Pancreatic neuroendocrine tumours arise from islet-type cells and are graded by mitotic rate and Ki-67 into G1, G2 and G3 well-differentiated tumours, distinct from poorly differentiated neuroendocrine carcinomas. Most are non-functioning and discovered as masses or metastases; functioning tumours announce themselves by a hormone syndrome. Sporadic tumours often carry MEN1, DAXX or ATRX mutations and mTOR pathway changes; syndromic ones occur in MEN1, VHL, NF1 and tuberous sclerosis.
Structure
- Gross: well-circumscribed, soft, red-tan nodules; larger tumours can invade or be cystic.
- Micro: nests, trabeculae or gyriform ribbons of uniform cells with salt-and-pepper chromatin.
- Immunohistochemistry: chromogranin A and synaptophysin; specific hormones by stain; Ki-67 for grade.
- Malignancy is judged by invasion and metastasis, mainly to liver; size and grade predict behaviour.
Functioning pancreatic neuroendocrine tumours
| Tumour | Hormone | Syndrome | Behaviour |
|---|---|---|---|
| Insulinoma | Insulin | Fasting hypoglycaemia: confusion, sweating, relief with glucose | Mostly benign |
| Gastrinoma | Gastrin | Zollinger-Ellison: refractory, multiple or jejunal ulcers, diarrhoea | Often malignant; frequent in MEN1 |
| Glucagonoma | Glucagon | Diabetes, necrolytic migratory erythema, anaemia, thrombosis | Usually malignant |
| VIPoma | Vasoactive intestinal peptide | Watery diarrhoea, hypokalaemia, achlorhydria | Often malignant |
| Somatostatinoma | Somatostatin | Diabetes, gallstones, steatorrhoea | Often malignant |
| Non-functioning | None effective (often pancreatic polypeptide) | Mass, jaundice, liver metastases | Variable |
Markers
- Chromogranin A
- Synaptophysin
- INSM1
- Ki-67
- Insulin, gastrin, glucagon stains
- Loss of DAXX or ATRX
Clinical notes
- Islet cell hyperplasia, sulfonylurea use and factitious insulin are differentials for hypoglycaemia; C-peptide separates exogenous insulin.
- In MEN1, multiple small tumours throughout the pancreas and duodenum are typical.
Test yourself
Think of the answer, then tap the question to see it.
What separates a G3 neuroendocrine tumour from a neuroendocrine carcinoma?
Both have a high proliferation index, but a G3 tumour is well differentiated, whereas a carcinoma is poorly differentiated (small or large cell).
Which tumour causes multiple refractory peptic ulcers and diarrhoea?
Gastrinoma (Zollinger-Ellison syndrome).
How does C-peptide help in hypoglycaemia caused by insulin?
It is high when insulin comes from the patient's beta cells (insulinoma, sulfonylurea) and low when insulin is injected.
Elsewhere in DurgiPedia
- Islets of Langerhans: α, β, δ cells
- Grading and staging: what TNM means
- Immunohistochemistry: the principle and the markers to know
Connections
Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Pancreatic Neuroendocrine Tumors (Islet Cell Tumors) Treatment (PDQ®)–Health Professional Version (National Cancer Institute, 2025); Insulinoma: MedlinePlus Medical Encyclopedia (MedlinePlus, US National Library of Medicine, 2025); Multiple endocrine neoplasia: MedlinePlus Genetics (MedlinePlus, US National Library of Medicine, 2025).
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Representative model, for educational purposes only.