Carcinoid Tumor

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