Introduction Tumor of neuroendocrine origin most common small bowel tumor Location most common sites are the rectum and stomach these foregut and hindgut masses rarely metastasize most common site of metastatic primary mass is terminal ileum appendix is common tumor site but too small to metastasize location determines whether or not carcinoid syndrome is present no carcinoid syndrome if the mass has not metastasized to the liver liver metabolizes 5-HT arriving in the portal circulation carcinoid syndrome is observed if tumor exists outside GI system Pathophysiology often produce 5-HT ectopically can lead to carcinoid syndrome Evaluation Biopsy dense core bodies seen on EM bodies are secretory granules bright yellow tumor Urinalysis 5-HT degraded to 5-HIAA and may be detected in the urine Treatment Pharmacologic hormone therapy somatostatin analogue to prevent extra hormones from being produced octreotide or lanreotide can help lessen flushing and diarrhea radiation and chemotherapy Surgical surgical resection can be done endoscopically, with local excision or with cryosurgery