Sites of carcinoid tumours

Carcinoid tumours may occur where there are Kulchitsky cells:

• gastrointestinal tract - in order of frequency:
  
  
• mid-gut:
  • 60% of cases
  • particularly distal third of appendix and terminal ileum
  • rarely in a Meckel's diverticulum
    
    
• hindgut:
  • 10-20% of cases
  • usually rectum
    
    
• foregut:
  • 10-20% of cases
  • mainly stomach, but also duodenum and oesophagus
    
    
• outside the GI tract:
  • bronchus
  • testes
  • ovaries

Potential to metastasise is related to site and size:

• appendix 3% metastasise, ileum 30% metastasise
• less than 1 cm, 2% metastasise; 1-2 cm, 50% metastasise; more than 2 cm, 80% metastasise

Appendiceal carcinoids are rarely multiple; ileal carcinoids are multiple in 30%.