carcinoid syndrome Flashcards
definition of carcinoid syndrome
constellation of symptoms caused by systemic release of humoral factors (biologic amines, polypeptides, prostaglandins) from carcinoid tumours
aetiology fo carcinoid syndrome
slow growing neuroendocrine tumours
mostly derived from serotonin producing enterochromaffin cells
produce: serotonin, histamines, tachykinins, kallikrein and prostaglandin, bradykinin, substance P, VIP, gastrin, insulin, glucagon, ACTH (Cushing’s syndrome), PTH, thyroid hormone
may be classified into fore-, mid- or hindgut tumours
75-80% people with carcinoid syndrome have small bowel tumours
common sites: appendix, ileum, rectum - both benign and non-secretory usually
also found in other parts of large intestine, stomach, thymus, bronchus and other organs (ovary, testis)
hormones released into portal circulation are metabolised in liver
symptoms dont appear until hepatic met (= secretion into hepatic veins) or release into the systemic circulation from bronchial or extensive retroperitoneal tumours
epidemiology of carcinoid syndrome
rare
uk incidence 1 in 1million/yr
asymptomatic are more common - incidental finding on rectal biopsy/appendectomy
10% people with multiple endocrine neoplasia (MEN) type 1 have carcinoid tumours
10% carcinoid tumours occur with other neuroendocrine tumours
carcinoid syndrome occurs in 5% people with carcinoid tumours - implies hepatic involvement
sx of carcinoid syndrome
paroxysmal flushing - especially in upper body +- migrating weals
diarrhoea
crampy abdo pain
wheeze
sweating
palpitations
signs of carcinoid syndrome
facial flushing
telangectasia
wheeze
R sided heart murmur - tricuspid stenosis, regurg or pul stenosis from 5HT-induced fibrosis = CCF
nodular hepatomegaly when mets
bronchoconstriction
carcoinoid crisis: profound flushing, bronchospasm, tachycardia, fluctuating BP
Ix for carcinoid syndrome
24hr urine - 5-HIAA levels (metabolite of serotonin) - false high with banana, avocado, caffeine, paracetamol
blood - plasma chromgranin A and B (reflects tumour mass), fasting gut hormones
CXR + chest/pelvis CT or MRI - localise tumour
radioisotope scan - Radiolabelled somatostatin analogue (e.g. indium-111 octreotide) and PET - localise
investigations for MEN-1
echo and BNP used to investigate carcinoid heart disease
what are carcinoid tumours
diverse group of tumours of enterochromaffin cell (neural crest) origin
capable of producing 5HT
sx and signs of carcinoid tumours
initially few
can cause appendicitis, intussesception or obstruction
hepatic met can = RUQ pain
summarise carcinoid crisis
when tumour outgrows blood supply or handled too much during surgery, mediators flood out
= life threatening vasodilation, hypotension, tachycardia, bronchoconstriction, hyperglycaemia
