Symptoms of neuroendocrine tumors

clinical presentation of neuroendocrine tumors

Neuroendocrine tumors are classified as well-differentiated (i.e., carcinoid tumors, pancreatic islet cell tumors) or as more aggressive, poorly differentiated tumors (i.e., carcinomas). Most are sporadic but can be associated with hereditary syndromes like multiple endocrine neoplasia 1 (MEN1). They typically secrete substances such as chromogranin A and pancreatic polypeptide. They can be further characterized based on their functional status (i.e., hormone secretion) and clinical manifestation. However, the majority of neuroendocrine tumors are nonfunctional. They present later in the disease process (i.e., larger tumors, metastasis) with symptoms of abdominal pain, weight loss, nausea, or obstructive symptoms.

Pancreatic Neuroendocrine Tumors

HormoneClinical ManifestationDiagnosisAdditional Treatment
InsulinomaInsulinHypoglycemiaHigh insulin and C-peptide level associated with low glucose levelsGlucose to avoid hypoglycemia; diazoxide reduces insulin secretion
Gastrinoma (i.e., Zollinger-Ellison syndrome)GastrinPeptic ulcer disease, secretory diarrheaElevated gastrin level > 1000 pg/mL
Secretin stimulation test if gastrin level < 1000 pg/mL (i.e., gastrin increases with stimulation)
Proton pump inhibitors to block acid secretion
GlucagonomaGlucagonNecrolytic migratory erythema, cheilitis, diabetes, anemia, weight loss, diarrheaGlucagon > 500 pg/mLTotal parenteral nutrition to address catabolic state
SomatostatinomasSomatostatinAbdominal pain, weight loss, diabetes, diarrhea, and gallbladder stonesFasting somatostatin level > 160 pg/mL—-
VIPomasVIPWatery diarrhea, hypokalemia, and hypochlorhydriaVIP > 75 pg/mLCorrect fluid loss and replace electrolytes; somatostatin analog to reduce VIP levels and improve diarrhea

VIP, Vasoactive intestinal peptide; VIPoma, vasoactive intestinal peptide tumor.

Carcinoid Tumors

LocationHormoneCarcinoid SyndromeAssociated Features
Majority nonfunctional
Elevated gastrin (5%) Histamine
Rare (associated with liver metastasis and bronchial carcinoids)Atrophic gastritis
Pernicious anemia
Zollinger-Ellison syndrome
MidgutSmall intestine
Proximal colon
Vasoactive substances (i.e., histamines, tachykinins, kallikrein, prostaglandin)
Classic presentation (associated with liver metastasis)Abdominal pain
DistalDistal colon
NonsecretoryRare (associated with tumors of the ovary and testes)Change in bowel habits Obstruction

MEN, Multiple endocrine neoplasia.


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