Pancreatic neuroendocrine tumors (PanNETs)
Pancreatic neuroendocrine tumors (PanNETs) are islet-cell tumors that may be functional, producing a hormone-excess syndrome such as insulinoma or gastrinoma, or nonfunctioning and detected by mass effect or incidentally. First-line treatment is surgical resection when localized, with somatostatin analogues and acid suppression used to control hormone-excess symptoms before or in place of surgery.
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What this article covers
- Overview
Definition: pancreatic neuroendocrine tumors (PanNETs) are tumors of the pancreatic islet cells that either secrete a hormone in excess, producing a distinct clinical syndrome, or remain…
- Epidemiology
Rarity: PanNETs are an uncommon subset of pancreatic tumors, far less common than pancreatic adenocarcinoma.
- Risk factors
MEN1 germline mutation: a pathogenic MEN1 (menin) mutation is the principal recognized genetic risk factor, predisposing to multifocal, earlier-onset PanNETs alongside parathyroid and pituitary tumors.
- Pathophysiology
Islet-cell origin: PanNETs arise from the hormone-producing cells of the pancreatic islets (or, for gastrinoma and somatostatinoma, from closely related duodenal enteroendocrine cells), retaining the…
- Clinical features
Insulinoma triad (Whipple triad): the diagnostic core feature of insulinoma is documented hypoglycemia on venipuncture, symptoms consistent with hypoglycemia (sweating, palpitations, anxiety, tremor…
- Differential diagnosis
Pancreatic adenocarcinoma: presents with obstructive jaundice, weight loss, and a nontender palpable gallbladder (Courvoisier sign), unlike the hormone-excess syndrome or islet-cell histology of a PanNET.
- Diagnosis
Diagnostic basis: the diagnosis of a functional PanNET rests on demonstrating an inappropriately elevated level of the relevant hormone in the setting of its clinical syndrome; nonfunctioning PanNETs…
- Management
First, resect the tumor surgically when it is localized and resectable: surgical resection is curative or disease-modifying for every PanNET subtype and is the definitive first-line treatment whenever the tumor can be removed.
- Complications
Metastatic disease: gastrinomas and VIPomas carry substantial malignant potential and most often metastasize to the liver, which can preclude curative surgery.
- Prognosis
Insulinoma has an excellent prognosis: because insulinomas are usually benign and solitary, surgical resection is typically curative.
- Prevention
Cascade genetic testing in MEN1 families: once a familial MEN1 mutation is identified, testing first-degree relatives allows carriers to begin surveillance for PanNETs and other manifestations before symptomatic disease develops.
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