Immunohistological localization of AFP and HCG in uniformly classified testis tumors.

Sixty seven germ cell tumors were studied for the presence of AFP and HCG by an immunoperoxidase technique. In the tumor tissues of 30 patients with seminomas no AFP-positivity was found, and in one case HCG positive giant cells were seen. In nonseminomatous tumors 54% were AFP-positive and 51% were HCG-positive. HCG was localized in syncytiotrophoblastic-like giant cells, occurring in choriocarcinomatous elements and as single cells in embryonal carcinomas, teratocarcinomas, and yolk sac tumors. AFP was demonstrable in 12 endodermal sinus tumor elements and, additionally, in solid cell clusters in embryonal carcinoma areas, arising as a component of a mixed germ cell tumor. In pure embryonal carcinomas we could not detect any positivity for either of the markers.