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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.
Carcinoid Tumors
Location | Hormone | Carcinoid Syndrome | Associated Features | |
---|---|---|---|---|
Foregut | Stomach Duodenum Pancreas Lung | Majority nonfunctional Elevated gastrin (5%) Histamine | Rare (associated with liver metastasis and bronchial carcinoids) | Atrophic gastritis Pernicious anemia Zollinger-Ellison syndrome MEN1 |
Midgut | Small intestine Proximal colon Appendix | Serotonin Vasoactive substances (i.e., histamines, tachykinins, kallikrein, prostaglandin) | Classic presentation (associated with liver metastasis) | Abdominal pain Obstruction Intussusception |
Distal | Distal colon Rectum Genitourinary | Nonsecretory | Rare (associated with tumors of the ovary and testes) | Change in bowel habits Obstruction Bleeding |
MEN, Multiple endocrine neoplasia.