Radiology of primary intracranial yolk-sac (endodermal sinus) tumors.

Most primary intracranial germ-cell tumors are germinomas and teratomas. Less frequent are embryonal carcinomas, choriocarcinomas, and yolk-sac (endodermal sinus) tumors in various admixtures and degrees of purity. Teilum [1] first used the term endodermal sinus tumor in 1959 to describe those tumors (whether ovarian, testicular, or extragonadal) that originate in primitive germ cells of extraembryonic origin and demonstrate selective overgrowth of yolksac elements. The reported incidence of intracranial germcell tumors ranges from 0.4% to over 3.4% of intracranial neoplasms [2]. From a review of two pure and three mixed cases of endodermal sinus tumor out of 4,000 intracranial tumors, Albrechtsen et al. [3] conc luded that intracranial yolk-sac carcinoma is a true pathologic entity expected to constitute over 0 .1 % of intracranial tumors and about 10%