Pancreatic neuroendocrine tumor (PNET) is defined as islet cell tumors of the pancreas that make islet cell type hormones. PNET can be functional or non-functional.
Functional: (means the tumor made hormones cause symptoms and show elevation)
Insulinoma, Gastrinoma, Glucagnoma, VIPoma
Most functional are more benign but still difficult to predict behavior and require close follow up.
Non-functional: (hormones released do not cause symptoms or no elevation of hormone at all)
Does not see elevation of or hyperhormonal symptoms
Most non-functional are more malignant (determined based on metastasis) because difficult to predict behavior.
Cause and risk factors/Association:
MEN1 gene mutation has been associated with increased risk of endocrine tumors
Symptoms and Diagnosis of Pancreatic Neuroendocrine Tumors:
Non-functional:
Indigestion, diarrhea, epigastric/abdomen pain, jaundice, palpable mass at right upper quadrant that is usually non-tender.
Functional
Symptoms of excess hormones production depending on the type of hormones being excessively produced
Insulinoma:
Usually benign solitary (arise from beta cells), elevated insulin levels
Hypoglycemia especially post fasting and relieved with glucose in take
Whipple Triad (Low sugar, Hypoglycemia Symptoms, Reversal of Symptoms with Glucose)
Gastrinoma (ZES) : see ZES section
Multiple ulcers (esophagus, stomach, duodenum, jejunum), elevated gastrin levels.
Can also arise from duodenum and peripancreatic tissues
Hypergastrenemia with ulcers refractory to conventional treatment.
Zollinger Ellison Syndrome (ZES): multiple duodenal ulcer, steatorrhea, prominent gastric rugal fold due to increase oxyntic gland mass
VIPoma
Tumors cells that produce excess VIP (vasoactive intestinal peptide)
Achlorhydria (low acid secretion from VIP);
Vasodilation (flushing, hypotension), nausea vomiting, weakness.
Hyperglycemia (due to increased glycogenolysis), hypercalcemia (due to increased bone resorption)
Watery Diarrhea with hypokalemia (hence muscle weakness), hypotension (due to loss volume).
Increased potassium secretion
Labs: stool studies show Osmolar gap < 50mOsm/kg, increased potassium ( Na+ )
Diagnosis: VIP > 75 pg/ml confirms and watery diarrhea). CT abdomen (pancreatic lesion usually found on the tail of pancreas)
Lab Markers and Morphological features
See hormones for Functional PNET
Progression and Course of Disease
Hard to predict and need close monitoring.
Treatment and Management
Surgical resection for localized lesion (whipple procedure)
Some patient can choose the wait and watch approach if the lesion does not show aggressive behavior.
Chemotherapy if metastatic.
Tags