Carcinoid Syndrome – At A Glance

Carcinoid syndrome is a rare neuroendocrine tumors that secrete certain chemicals into the blood stream.

Some carcinoid tumors can be cancerous, while some are non cancerous.
Only functioning carcinoid tumors can produce carcinoid syndrome by secreting chemicals into the bloodstream (Serotonin, ACTH, etc).

Carcinoid tumors have a vague presentation, therefore it is very hard to diagnose.

Carcinoid syndrome usually occurs when there is hepatic metastasis where it releases serotonin into the bloodstream.

Commonly these tumors are seen in the appendix, but can be seen in other sites as well.

Incidence :1 in 100 000 individuals
Commonly seen in adults and very rare in children

Aetiology : Unknown

Distribution Of Carcinoid Syndrome

  • Gastrointestinal tract – 54.5%
    • Appendix – 26%
    • Small intestine – 39%
    • Rectum – 15%
    • Colon – 5 – 7%
  • Lungs and bronchus – 30.1%
  • Pancreas 2.3%
  • Ovary (1.2%) 
  • Biliary (1.1%)
  • Head and neck (0.4%)
  • Others

Classification Of Carcinoid Tumors
On the basis of the location in primitive gut
  • Foregut carcinoid tumors
  • Midgut carcinoid tumors
  • Hindgut carcinoid tumros
Clinical Presentation Of Carcinoid Syndrome
  • Periodic abdominal pain 
  • Cutaneous flushing
  • Diarrhoea and malabsorption 
  • Cardiac manifestation
    • Hypotension 
    • Right hear valvular stenosis – Tricupid stenosis
    • Bronchial carcinoid affects the left heart 
  • Rare presentations 
    • Respiratory manifestations
      • Cough
      • Wheezing
      • Dyspnoea
    • Pellegra 
      • Due to tryptophan deficiency caused by the carcinoid tumor as it is diverted to serotonin by the tumor
    • ACHT producing tumors – Cushing’s syndrome 
Investigations Of Carcinoid Syndrome
  • Incidental diagnosis 
    • Usually during appendectomy 
    • Confirmed by the histopathologist
  • Elevated amine levels
    • 5-hydroxyindoleacetic acid (5-HIAA)
    • Chromographin-A
    • Serotonin
  • Imaging studies
    • To identify the site and metastasis

Management Of Carcinoid Syndrome
  • Surgical excision of the carcinoid tumor
  • Chemotherapy
  • Medical management
    • Octreotide – Reduce the secretion of serotonin from the tumor
    • Cyproheptadine – For diarrhoea 
      • (Anti-histamine, anticholinergic, antiserotonergic, and local anesthetic effects are present in cyproheptadine)
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