Cellular localization of alpha‐fetoprotein and human chorionic gonadotropin in germ cell tumors of the testis using an indirect immunoperoxidase technique. A new approach to classification utilizing tumor markers
An immunohistologic study of 21 patients with germ cell tumors of the testis with measured serum levels of chorionic gonadotropin (HCG) and alpha-feto protein (AFP) was undertaken to correlate the various types of neoplasms with the presence of these tumor markers in the tissue and serum. AFP was demonstrated in mononuclear embryonal cells within embryonal carcinoma and endodermal sinus tumor. HCG was identified within syncytiotrophoblastic giant cells, frequently in association with embryonal carcinoma, and rarely with endodermal sinus tumor and seminoma, as well as in the syncytiotropho-blastic component of choriocarcinoma. Eighteen of the 21 patients (86%) had elevated tumor markers in their serum; serum HCG alone was elevated in five (24%), AFP alone in five (24%) and both were elevated in eight (38%). There was tissue localization of HCG in 12 of the 13 patients (92%) with elevated serum HCG while AFP was identified in the tumor in eight of the 13 patients (53%) with elevated serum AFP levels. Based on these findings, a tentative immunohistologic classification of germ cell tumors utilizing AFP and HCG is proposed. Thus, embryonal carcinoma, adult type, is frequently associated with both AFP and HCG, endodermal sinus tumor with AFP and choriocarcinoma with HCG, whereas pure seminoma and teratoma are unlikely to be associated with either marker.