Malignant carcinoid syndrome

Regarding malignant carcinoid syndrome, the following statements are true EXCEPT

which one?

a) Malignant carcinoid syndrome occurs in around 50% of those patients with a

carcinoid tumour

b) Fibrosis of heart valves is more commonly seen on the right side of the heart than

the left

c) Carcinoid tumours can produce insulin

d) For a patient to have malignant carcinoid syndrome they are likely to have liver

metastases

e) Carcinoid tumours originating in the appendix are likely to be benign

Answer: a

Explanation

The term carcinoid can be applied to all tumours of the diffuse endocrine system.

Carcinoid tumours may produce a wide variety of vasoactive substances, polypeptides

and amines including histamine, somatostatin, 5-hydroxytryptamine and very rarely

insulin. Malignant carcinoid syndrome (MCS) is the constellation of symptoms typically

exhibited by patients where the vasoactive substances they produce bypass and

hence are not broken down by the liver. This circumstance usually arises in those

patients with metastatic liver deposits, but is not exclusively limited to it (e.g. bronchial

carcinoid tumours). MCS occurs in around 15% of patients with a carcinoid tumour.

Patients with MCS can present a significant anaesthetic challenge. Their clinical presentation

mainly depends on the site(s) of the tumour(s) and the substance(s) they

secrete. Flushing, diarrhoea and bronchospasm are the commonest presenting features.

Greater than 90% of carcinoid tumours originate from the distal ileum of

appendix. Those originating from outside the gut have the highest incidence of MCS.

Patients with MCS tend to have right-sided heart problems including tricuspid and

pulmonary valve lesions and right-sided heart failure, as the vasoactive substances are

metabolised by the lungs so tend not to reach the left side of the heart.