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
|Hormone||Clinical Manifestation||Diagnosis||Additional Treatment|
|Insulinoma||Insulin||Hypoglycemia||High insulin and C-peptide level associated with low glucose levels||Glucose to avoid hypoglycemia; diazoxide reduces insulin secretion|
|Gastrinoma (i.e., Zollinger-Ellison syndrome)||Gastrin||Peptic ulcer disease, secretory diarrhea||Elevated 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|
|Glucagonoma||Glucagon||Necrolytic migratory erythema, cheilitis, diabetes, anemia, weight loss, diarrhea||Glucagon > 500 pg/mL||Total parenteral nutrition to address catabolic state|
|Somatostatinomas||Somatostatin||Abdominal pain, weight loss, diabetes, diarrhea, and gallbladder stones||Fasting somatostatin level > 160 pg/mL||—-|
|VIPomas||VIP||Watery diarrhea, hypokalemia, and hypochlorhydria||VIP > 75 pg/mL||Correct fluid loss and replace electrolytes; somatostatin analog to reduce VIP levels and improve diarrhea|
VIP, Vasoactive intestinal peptide; VIPoma, vasoactive intestinal peptide tumor.
|Location||Hormone||Carcinoid Syndrome||Associated Features|
Elevated gastrin (5%) Histamine
|Rare (associated with liver metastasis and bronchial carcinoids)||Atrophic gastritis|
Vasoactive substances (i.e., histamines, tachykinins, kallikrein, prostaglandin)
|Classic presentation (associated with liver metastasis)||Abdominal pain|
|Nonsecretory||Rare (associated with tumors of the ovary and testes)||Change in bowel habits Obstruction|
MEN, Multiple endocrine neoplasia.