Carcinoid Syndrome

Question 1

Definition

Answer 1

Constellation of symptoms caused by systemic release of humoral factors from carcinoid tumours

Question 2

Aetiology

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

Question 3

Epidemiology

Answer 3

· RARE
· UK incidence : 1/1,000,000
· Asymptomatic carcinoid tumours are more common
· 10% of patients with MEN-1 have carcinoid tumours

Question 4

Presenting symptoms

Answer 4

· Paroxysmal FLUSHING
· Diarrhoea
· Crampy abdominal pain
· Wheeze
· Sweating
· Palpitations

Question 5

Signs on physical examination

Answer 5

· Facial flushing
· Telangiectasia
· Wheeze
· Right-sided murmurs (tricuspid stenosis/regurgitation or pulmonary stenosis)
· Nodular hepatomegaly in cases of metastatic disease

Question 6

Carcinoid crisis signs

Answer 6

o Profound flushing
o Bronchospasm
o Tachycardia
o Fluctuating blood pressure

Question 7

Investigations

Answer 7

· 24 hours urine collection
o Check 5-HIAA levels (metabolite of serotonin)

· Blood
o Plasma chromogranin A and B
o Fasting gut hormones

· CT or MRI Scan
o To localise the tumour

· Radioisotope Scan
o Radiolabelled somatostatin analogue helps localise the tumour

· Investigations for MEN-1