ALPHA‐FETOPROTEIN (AFP) AND HUMAN CHORIONIC GONADOTROPIN (HCG) IN TESTICULAR GERM CELL TUMOURS

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Abstract
A total of 189 orchidectomy specimens with germ cell tumors (95 pure seminomas and 94 nonseminomas) were studied for the presence of .alpha.-fetoprotein (AFP) and human chorionic gonadotropin (HCG) with the indirect immunoperoxidase technique. All seminomas were AFP negative, while 66% of the nonseminomas were positively stained for AFP. Some 21% of pure embryonal carcinomas (EC), 25% of EC components in mixed tumors, all yolk sac tumor (YST) components, 20% of pure teratomas (T) and 47% of T components were AFP positive. In EC and YST the immunohistochemical staining depicted characteristic previously unrecognized histological structures, presumably representing patterns of further differentiation. HCG was demonstrated in all choriocarcinoma (CC) components in the syncytiotrophoblasts and in syncytiotrophoblast-like cells (STLC) in 8% of seminomas and 30% of nonseminomas. Of all nonseminomatous tumors, 70% were positively stained for AFP and/or HCG. Neither AFP nor HCG positivity of the tumor tissue was especially associated with metastatic disease. Carcinoma-in-situ present in seminiferous tubules adjacent to the tumors was never positively stained for AFP, but for HCG in a few cases.