Fact-sheet: Pancreatic neuroendocrine tumor


Updated on 02/22/2024 at 1:41 PM

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Definition

Rare tumor (2% of pancreatic tumors) arising from the endocrine cells of the Pancreas. Pathology: firm, well-defined lesion. Diagnosis based on immunohistochemistry. Three histologic grades: benign / uncertain / carcinoma. Prognosis: depends on differentiation, the most suggestive features being: - histologic grade (poorly differentiated, high mitotic and proliferation index (Ki67)), presence of metastases++ - Size: >3cm for insulinoma and nonfunctioning tumors, >1-2cm for others - Type of secretion (malignancy rate 90% for gastrinomas, 80% for glucagonomas, 60% for VIPomas, 60% for insulinomas, 10% for nonfunctioning tumors)

Clinical features

Median age 65, M/F=1,
sporadic in 95% of cases.
Otherwise associated with MEN1, VHL, TSC

Earlier detection of functioning forms due to paraneoplastic syndrome -
Functioning tumors:
Gastrin: gastroduodenal ulcers and diarrhea (Zollinger-Ellison syndrome);
Insulin: organic Low bloog glucose Hypoglycemia;
VIP: diarrhea, hypokalemia (Werner-Morrison syndrome);
Glucagon: diabetes, cachexia;
Somatostatin: gallstones, diabetes, steatorrhea -
Nonfunctioning tumors:
weight loss, jaundice, pain...

Ultrasound

Echogenic, well-defined mass, without involvement of the main duct (except for intraductal NETs)

CT

Late arterial phase (pancreatic phase+++)
- Typical form: small, hypervascular tumor without washout, well-defined
- Nonfunctioning and/or high-grade form: large, heterogeneous, hypovascular, with possible calcifications and vascular invasion
-
Purely cystic form: rarest form; hypervascular walls, large size and heterogeneity are suggestive of malignancy+++.
Locoregional and distant staging

MRI

T1 hypointense, T2 hyperintense, diffusion hyperintense.
Hypervascular tumor without washout following IV gadolinium administration

Nuclear medicine

Somatostatin receptor scintigraphy

Management

Endoscopic ultrasound: highly sensitive, reference standard for lesions < 10 mm, fine-needle aspiration