[Importance of immunohistochemistry for neuro-oncology. IV. Distribution model of beta human chorionic gonadotropins in intracranial germ cell tumors].

beta-Human choriogonadotropic hormone (beta-HCG) is considered a good marker for trophoblastic differentiation of germ cell tumors. 34 primary intracranial germ cell tumors (15 germinomas, 6 mature teratomas, 1 embryonal carcinoma, 2 endodermal sinus tumors and 10 mixed germ cell tumors) were immunohistochemically evaluated for the presence of beta-HCG positive cells. In 8 of 15 germinomas and 6 of 10 mixed germ cell tumors beta-HCG cells were demonstrable. In the germinomas such cells included both syncytiotrophoblastic and mononuclear cells which histologically did not correspond to the cytotrophoblast. In one case the patient had exhibited a precocious puberty. Of the 6 beta-HCG positive mixed germ cell tumors, two contained elements of choriocarcinoma. In the cytotrophoblasts of the choriocarcinoma regions, beta-HCG was only sparsely demonstrable. Both of these patients had manifest precocious puberty clinically. The advantage of immunohistochemical demonstration of the beta-HCG compared to conventional histology is in the definite identification of trophoblastic differentiation, in particular the exact recognition of the choriocarcinoma segments, which can be critical for the prognosis. Demonstration of isolated syncytiotrophoblasts and beta-HCG positive mononuclear cells in the seminomas is of no prognostic significance and is primarily of theoretical interest.