Malignant carcinoid syndrome
(Science: syndrome) a symptom complex associated with carcinoid tumour and characterised by attacks of severe flushing of the skin, diarrhoeal watery stools, bronchoconstriction, sudden drops in blood pressure, oedema, and ascites. The carcinoid tumours are usually located in the gastrointestinal tract and metastasize to the liver. Symptoms are caused by tumour secretion of serotonin, prostaglandins, and other biologically active substances. Cardiac manifestations constitute carcinoid heart disease.