Neuroendocrine tumour of the pancreas

Neuroendocrine tumour of the pancreas, also pancreatic neuroendocrine tumour, is a relatively uncommon tumour.

It may be abbreviated PanNET.

Previously, it was referred to as pancreatic islet cell tumour or islet cell tumour; thes terms are now considered to be outdated.

Neuroendocrine tumours in general are dealt with in the neuroendocrine tumours article.

General

• Rare ~ 1% of pancreatic tumours.
• Presentation depends on subtype, e.g. for insulinoma the typical presentation is hypoglycemia.
• May be part of a syndrome:
  • Multiple endocrine neoplasia I.
  • Von Hippel-Lindau disease.
  • Neurofibromatosis type 1.

Classification

Based on peptide produced in the pancreatic islets:

1. Glucagon from alpha cells (glucagonoma).
2. Insulin from beta cells (insulinoma) - most common ~ 50% of islet cell tumours.
3. Somatostatin from D cells (somatostatinoma).
4. Pancreatic polypeptide from PP cells.

Others:

1. Vasoactive intestinal peptide (VIPoma).
2. Gastrin (gastrinoma).
   • May be seen in Zollinger-Ellison syndrome.
     • Triad: pancreatic gastrinoma, gastric acid hypersecretion, marked peptic ulcers in the small bowel.

Gross

• Usually in the head of the pancreas - 68% in one series, and 50% in another series.

Microscopic

Features:

• Nests of cells.
• Stippled chromatin.
• +/-Hyaline globules.

DDx:

• Solid pseudopapillary neoplasm.
• Acinar cell carcinoma.

Images

www:

• Islet cell tumour (upmc.edu).
• Pancreatic NET with features of SPT (upmc.edu).
• Pancreatic NET - another case (upmc.edu).

IHC

• CK19 +ve -- should be done as a routine in pancreatic NETs; poor prognostic factor.

Note:

• CK19 should not be confused with CA19-9.

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TAIL OF PANCREAS AND SPLEEN, DISTAL PANCREATECTOMY AND SPLENECTOMY:
- CYSTIC PANCREATIC NEUROENDOCRINE TUMOUR.
- UNREMARKABLE SURROUNDING PANCREAS WITH FAT.
- SPLEEN WITHIN NORMAL LIMITS.
- FOUR BENIGN LYMPH NODES.
- NEGATIVE FOR MALIGNANCY.

Micro

The sections show pancreas with a large well-circumscribed tumour that centrally has a large cyst-like cavity. The tumour cells have moderate pale grey cytoplasm and round nuclei with salt and pepper chromatin. The tumour cells are arranged in cords and nests. No cholesterol clefts are readily apparent. No hyaline globules are identified. No papillary structures are apparent.

No necrosis is identified. No degenerative changes are apparent. Mitotic activity is seen focally. There are 2 mitoses per 10 high power fields, were one high power field has an area of 0.2376 mm*mm.

See also

• Pancreas.
• Neuroendocrine tumours.