Carcinoid Tumour Syndrome
Related Subjects:
|Zollinger Ellison syndrome
|VIPomas
|Carcinoid Tumour Syndrome
ℹ️ About
- Carcinoid Tumour Syndrome 🧬: Caused by excess secretion of serotonin and other vasoactive peptides from neuroendocrine tumours.
- Neuroendocrine tumours (NETs) are often slow-growing, arising from enterochromaffin (Kulchitsky) cells of the APUD system.
- Because serotonin is metabolised in the liver, syndrome usually occurs only after liver metastases 🩸.
- Most common in adults aged 50–70 years.
🧬 Aetiology
- 90% arise in the GI tract (appendix, ileum, rectum, colon).
- Also occur in the bronchi and rarely other sites.
- ~5% of NETs ➝ progress to carcinoid syndrome.
- Smaller tumours (<1 cm) rarely metastasise; those >2 cm often do 📏.
Risk Factors & Associations
- Genetic syndromes: MEN1 🧬, neurofibromatosis, tuberous sclerosis.
- Family history of neuroendocrine or squamous tumours.
🩺 Clinical Features
- Local tumour effects:
- Appendiceal ➝ mimic acute appendicitis.
- Rectal ➝ bleeding, constipation.
- Colonic ➝ abdominal pain, bleeding.
- Carcinoid syndrome (systemic due to serotonin ± histamine):
- 💨 Bronchospasm ➝ wheeze.
- 💩 Profuse diarrhoea.
- 😳 Episodic flushing of face/neck.
- ❤️ Carcinoid heart disease ➝ tricuspid regurgitation & pulmonary stenosis (due to endocardial fibrosis).
Differential Diagnoses
- IBD (Crohn’s, ulcerative colitis) ➝ diarrhoea, abdominal pain.
- Asthma ➝ wheeze, breathlessness.
- Other intermittent diarrhoeal illnesses (e.g. IBS, infections).
🔎 Investigations
- 🧪 5-HIAA (urinary): Elevated in carcinoid syndrome (avoid bananas, avocados, walnuts before test as they elevate serotonin metabolites).
- 🩸 FBC, U&E, LFTs, CRP: Baseline investigations, may show anaemia or deranged LFTs.
- 🔍 Octreotide (somatostatin receptor) scan: Localises primary tumour and metastases.
- 🫀 Echocardiogram: Screens for carcinoid heart disease.
- 📈 NT-proBNP: Marker of carcinoid valvular disease.
💊 Management
- Local disease: Surgical resection ➝ potentially curative ✂️.
- Metastatic disease: Hepatic artery embolisation or systemic chemotherapy.
- Symptom control:
- Octreotide (somatostatin analogue) ➝ reduces hormone secretion.
- Other options: Methysergide, Cyproheptadine (serotonin antagonists).
- Prognosis: Good if confined; poorer if widespread metastases.
References
