Malignant germ cell tumors of the ovary and testis. An immunohistologic study of 69 cases

An immunohistologic study of 21 patients germ cell tumors of the testis with measured serum levels of human chorionic gonadotropin (HCG) and alpha fetoprotein (AFP) was undertaken to correlate the various types of neoplasms with the presence of these tumor markers in the tissue and serum. The same immunoperoxidase technique ws applied to 48 patients with malignant germ cell tumors of the ovary in whom serum was not available. In the testicular tumor group, 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 syncytiotrophoblastic component of choriocarcinoma. Eighteen of the 21 patients (86 percent) had elevated tumor markers in their serum; serum HCG alone was elevated in 5 (24 percent) AFP alone in 5 (24 percent) and both were elevated in 8 (38 percent). There was tissue localization of HCG in 12 of 13 patients (92 percent) with elevated serum HCG while AFP was identified in the tumor in eight of the 13 patients (53 percent) with elevated serum AFP levels. In the ovarian tumor group, all 15 endodermal sinus tumors examined were positive for AFP and negative for HCG. Seven of 10 embryonal carcinomas were positive for AFP and all 10 were positive for HCG. The two cases of choriocarcinoma were both positive for HCG and negative for AFP. In contrast, the 11 dysgerminomas and 10 teratomas were negative for both AFP and HCG. The results parallel those for malignant germ cell tumors of the testis, affording additional evidence of the analogous nature of germ cell tumors of the gonads. Based on these findings a tentative immunohistologic classification of germ cell tumors utilizing AFP and HCG is proposed. Thus, embryonal carcinoma is frequently associated with both AFP and HCG, endodermal sinus tumor with AFP and choriocarcinoma with HCG, whereas pure seminoma, dysgerminoma and teratoma are unlikely to be associated with either marker.