Presentation of nonpancreatic GI neuroendocrine tumors (carcinoid tumors)
- Carcinoid tumors can occur in many different organs throughout the body but most commonly occur in the GI tract (approximately 70% of the time).
- Within the GI tract, the most common locations, listed in descending order, are the small intestine, rectum, appendix, large intestine, and stomach.
- Neuroendocrine tumors of the small intestine are the most likely to cause carcinoid syndrome, which typically does not occur until the patient has developed metastases to the liver.
- These tumors frequently result in a desmoplastic (fibrotic) reaction of the adjacent mesentery, causing bowel obstructions.
- Hindgut carcinoids do not usually produce active hormones and are typically found incidentally during endoscopy performed for other reasons.
- Gastric carcinoids are also frequently found incidentally on endoscopy but may cause such symptoms as pain or bleeding.