n. a tumour that contains *APUD cells and may give rise to symptoms caused by excessive production of the hormones and other peptides that these cells produce. *Carcinoids are a good example of this group of tumours, but there are many others (e.g. *gastrinomas, *somatostatinomas, and *VIPomas).
n. a tumour of the *argentaffin cells in the glands of the intestine (see apudoma). Carcinoids typically occur in the tip of the appendix and are among the commonest tumours of the small intestine. They may also occur in the rectum and other parts of the digestive tract and in the bronchial tree (bronchial carcinoid adenoma). Carcinoids sometimes produce 5-hydroxytryptamine (serotonin), prostaglandins, and other physiologically active substances, which are inactivated in the liver. If a gastrointestinal tumour has spread to the liver, excess amounts of these substances are released into the systemic circulation and the carcinoid syndrome results – flushing, headache, diarrhoea, bronchial constriction causing asthma-like attacks, and in some cases damage to the right side of the heart associated with fibrosis of the tricuspid valve. Bronchial carcinoids can give rise to the syndrome without metastasizing.... carcinoid
n. a rare tumour of the *islets of Langerhans that produces excessive amounts of somatostatin. It is an example of an *apudoma. In severe cases it can cause the somatostatinoma syndrome, consisting of diabetes, gall-bladder disease, and *steatorrhoea due to malabsorption.... somatostatinoma
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