argentaffinoma

n a tumour of the argentaffin cells in the glands of the intestine ( see apudoma ). Argentaffinomas 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). Argentaffinomas sometimes produce 5-hydroxytryptamine (serotonin), prostaglandins, and other physiologically active substances, which are inactivated in the liver. If the 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, asthma-like attacks, and in some cases damage to the right side of the heart.