Alpha-fetoprotein in germ cell tumors. An immunohistochemical study.

Total 40 cases of testicular and ovarian germ cell tumors and one case of extragonadal germ cell tumor were studied for the presence of alphafetoprotein (AFP) by indirect immunoperoxidase technique. All seminomas (7 cases) and teratomas (13 cases) were negative for AFP; while 85% of the pure embryonal carcinomas, (E.C.) all pure yolk sac tumors (Y.S.T.) (7 cases) and all embryonal carcinoma and yolk sac components in mixed tumors were AFP positive. Immunostaining of tumor marker appeared to help only in differentiating seminomatous and nonseminomatous tumors and hence does not provide any additional information for classification of these tumors.