A 45-year-old woman presents with flushing, diarrhea, and right heart valvular lesions. Urine 5-HIAA is markedly elevated. The responsible tumor most commonly arises in which location?
- A Appendix
- B Ileum ✓
- C Rectum
- D Stomach
Correct answer: B. Ileum
Explanation
Carcinoid syndrome with elevated urinary 5-HIAA indicates a metastatic carcinoid (well-differentiated neuroendocrine tumor) that has reached the liver, releasing serotonin into systemic circulation. The ileum is the most common site of carcinoids that produce carcinoid syndrome; appendiceal carcinoids are the most common carcinoid by site but rarely metastasize or produce the syndrome. Rectal carcinoids almost never secrete serotonin.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.