Carcinoid Syndrome

Question 1

Define Carcinoid Syndrome

Answer 1

Constellation of symptoms caused by systemic release of humoral factors (serotonin 5-hydroxytryptamine) + biogenic amines, polypeptides, prostaglandins) from carcinoid tumours

Carcinoid tumour = slow-growing neuroendocrine tumours that produce secretory products

Question 2

Aetiology Carcinoid Syndrome

Answer 2

Slow-growing neuroendocrine tumours mostly derived from serotonin-producing enterochromaffin cells -> produces serotonin, histamine, tachykinins, prostaglandins
75-80% - small bowel carcinoids
RF: MEN-1 syndrome

Hormones released into the portal circulation are metabolised in the liver -> symptoms do not appear until there are hepatic metastases or release into the systemic circulation

Question 3

Symptoms of Carcinoid Syndrome

Answer 3

Diarrhoea
Flushing (paroxysmal) - cutaneous e.g. face flushing 
Palpitations
Abdominal cramps
Wheeze
Sweating 

CARC:
Cutaneous flushing 
Asthmatic wheeze
Right sided murmur 
Cramps + diarrhoea

Question 4

Signs of Carcinoid Syndrome on examination

Answer 4

Signs of RHF
Cardiac murmurs: tricuspid stenosis, regurgitation, pulmonary stenosis
Hepatomegaly
Abdominal masses
Telengiectasia
Pellagra (inflamed skin, diarrhoea, dementia, sores in the mouth)

Question 5

Signs of carcinoid syndrome crisis

Answer 5

Profound flushing
Bronchospasm
Tachycardia
Fluctuating BP

Question 6

Investigations for Carcinoid Syndrome

Answer 6

24-h urine collection for 5-HIAA levels: elevated
Plasma chromagranin A and B: elevated

Metabolic panel: elevated creatinine
LFTs: Variable, depends on site of tumours
FBC: usually normal

CT/MRI CAP: identifies primary tumours + metastases
Echo: Identify any valve pathologies
MIBG: Identifies areas of tumour through MIBG take-up

Biopsy: identify tumour type
Endoscopy: may find primary tumour
Stomatostatin receptor scintigraphy ± SPECT: identifies areas of somatostatin receptor-positive tumours