Features of prognostic significance in testicular germ cell tumours.

One hundred and one testicular tumours previously diagnosed as "teratoma" were examined and 93 of the patients were followed up. These neoplasm were assigned to one of three groups. Those compared exclusively of somatic tissues were the only tumours referred to as teratoma. The second group was exclusively extra embryonic and consisted of either yolk sac or choriocarcinoma. Neoplasms in the third group were called mixed germ cell tumours and incorporated somatic and extra embryonic tissue and occasionally seminoma. The patients with teratomas showed a very low mortality whereas pure yolk sac tumours proved highly malignant. In mixed germ cells tumours the malignant nature of the yolk sac components was maintained even when combined with somatic elements, but when seminoma was also present the survival rate was significantly improved. It would appear the yolk sac tumour tissue occurs more frequently in adult testicular neoplasms than was previously suspected and in mixed germ cell tumours it can be expected to dictate behaviour except when combined with seminoma.