Summary: Of a group of 13 patients with carcinoid tumours, 10 were investigated biochemically during life, and 3 tumours were discovered post mortem. Nine of the 10 patients had significantly elevated levels of 5-hydroxytryptamine in blood platelets, but only 7 showed markedly increased levels of 5-hydroxyindoleacetic acid in urine. One of these patients excreted the precursor 5-hydroxytryptophpn, as well as 5-hydroxytryptamine and 5-hydroxyindoleacetic acid. Analysis of tumour tissue from this patient showed only low levels of 5-hydroxytryptamine (16 [mu]g/g) when compared with the levels from other carcinoid tumours (50-500 [mu]g/g). A primary tumour in this patient could not be located at autopsy. In another patient with widely disseminated metastases, a small primary tumour was found in a Meckel's diverticulum, a rare site of development. Of the 3 carcinoid tumours discovered post mortem, the first involved the appendix and right ovary; in the second case, multiple primary tumours occurred in the jejunum, while in the third, a small bronchial carcinoid was found which stored adrenalin and noradrenalin, but not 5-hydroxytryptamine. This is an unusual biochemical feature which, to our knowledge, has not previously been reported.
(C) 1973 Royal College of Pathologists of Australasia