[Ectopic production of chorionic gonadotropin in apudomas (author's transl)].

Two pheochromocytomas, two carcinoid tumours of the ileum and one pancreatic vipoma showed APUD-system properties and formed electron-dense secretory granules indicating synthesis and storage of proteohormones. Besides catecholamines, 5-hydroxytryptamine and vasoactive intestinal polypeptide, all five tumours contained immunoreactive chorionic gonadotropin and also its free, protomeric beta chain as a sign of de-differentiation. Plasma of the tumour patients also contained immunoreactive chorionic gonadotropin and the free protomeric beta chain, both of which are useful tumour markers.