- 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 |
| Bronchial
Gastric |
Jejunal
Ileal Appendicular |
Colonic
Rectal |
| 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).
