Carcinoid syndrome

Question 1

Define

Answer 1

Constellation of symptoms caused by systemic release of humoral factors (biogenic amines, polypeptides, prostaglandins) from carcinoid tumours

A diverse group of tumours of enterochromaffin cell (neural crest) origin, by definition capable of producing 5HT

Carcinoid syndrome occurs in ~5% of carcinoid tumours and implies hepatic involvement.

Symptoms

 Carcinoid tumours are slow growing neuroendocrine tumours
- mostly derived from serotonin-producing enterochromaffin
cells 

 They produce secretory products such as serotonin, histamine, tachykinins, kallikrein and prostaglandin

Question 2

Causes

Answer 2

Carcinoid tumours are slow-growing neuroendocrine tumours

They are mostly derived from serotonin-producing enterochromaffin cells

They produce secretory products like serotonin, histamine, tachykinins, kallikrein and prostaglandins

75-80% of patients with carcinoid syndrome have small bowel carcinoids

NOTE: hormones released into the portal circulation will be metabolised by the liver so symptoms don’t tend to appear until there are hepatic metastases or release into the systemic circulation from bronchial or extensive retroperitoneal tumours

Classified into fore-, mid- or hindgut tumours
↘ Appendix (45%), ileum (30%), rectum (20%)

Also found in other parts of large intestine, stomach, thymus, bronchus and other organs (ovaries, testis)

80% of tumours >2cm across will metastasise

Hormones released into the portal circulation are metabolized in the liver
→ Thus symptoms typically do not appear until there are hepatic metastases (resulting in the secretion of tumour products into the hepatic veins), or release into the systemic circulation from bronchial or extensive retroperitoneal tumours

Question 3

Epidemiology

Answer 3

RARE, UK 1/1 000 000

Carcinoid syndrome occurs in ~5% of carcinoid tumours and implies hepatic involvement.

Question 4

Symptoms

Answer 4

Paroxysmal FLUSHING

Diarrhoea

Crampy abdominal pain

Wheeze

Sweating

Palpitations

Question 5

Signs

Answer 5

Facial flushing

Telangiectasia

Wheeze

Right-sided murmurs (tricuspid stenosis/regurgitation or pulmonary stenosis)

Nodular hepatomegaly in cases of metastatic disease

Carcinoid Crisis Signs:

• Profound flushing
• Bronchospasm
• Tachycardia
• Fluctuating blood pressure

Question 6

Investigations

Answer 6

24 hours urine collection

• Check 5-HIAA levels (metabolite of serotonin)

Blood

• Plasma chromogranin A and B
• Fasting gut hormones

CT or MRI Scan

• To localise the tumour

Radioisotope Scan

• Radiolabelled somatostatin analogue helps localise the tumour

Investigations for MEN-1