Carcinoid tumors

  • Origin: Cells of Kulchitsky (enterochromaffin cell)
  • Carcinoid tumors are composed of multipotent cells with the ability to secrete numerous humoral agents, the most prominent of which are serotonin and substance P
  • Serotonin: 5-Hydroxy-Tryptamine (5HT)
  • Site:
    • MC system: GIT> Respiratory
    • Within GIT: Midgut > Hindgut > Foregut
    • MC individual organ: Appendix > Ileum > Bronchus > Rectum
Foregut Midgut Hindgut







Argentaffin -ve

Do not cause carcinoid syndrome

Argentaffin +ve

But serotonin produced is metabolized in liver, so does not cause carcinoid syndrome

Argentaffin +ve

May cause carcinoid syndrome

  • Chemical mediators (i.e. serotonin) produced by midgut carcinoids go to liver and metabolized to 5HIAA (Hydroxy indole acetic acid), which is excreted in urine
  • When chemical mediators are produced by secondaries in liver, they directly go to circulation and cause carcinoid syndrome (ileal carcinoids metastasize frequently)
  • If carcinoid syndrome is severe & life-threatening, it is called “Carcinoid crisis”. Rx: Octreotide.
  • Stomach carcinoids are associated with atrophic gastritis and MEN1
  • Highest malignant potential: Rectal carcinoid
  • MC symptom of carcinoid tumors: Flushing (due to vasodilation)
  • Investigation of choice (IOC) for localization of carcinoid tumors: Serotonin receptor scintigraphy (SRS)
  • Other investigation: Urinary 5HIAA level measurement
  • Cardiac lesions in Carcinoid tumor:
    • Due to subendocardial fibrosis
    • TR (MC) > PR > TS > PS (LC) [Reference: 19th Harrison, Page no. 564]
  • TOC: Surgical resection with 2 cm margin
  • Management of appendicular carcinoids:
    • If located on the tip: Simple appendicectomy
    • If located close of base: Right hemicolectomy
  • Chemotherapy: (Streptozocin + Adriamycin).

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