Endodermal sinus tumor of the pineal region: case report.

This is a case report of an endodermal sinus tumor occurring in the pineal region of a 12-year-old Caucasian boy. Germ cell tumors of this type demonstrate a selective overgrowth of yolk sac endoderm associated with extraembryonic mesoblast and arise perferentially in the gonads of young children. This is the ninth known report of this tumor in the world literature. Its occurrence in the posterior third ventricle again confirms that pineal region germ cell tumors are histologically analogous to germ cell tumors originating in the gonads. A disturbance in the region of the primitive streak is thought to account for the exclusive midline location of this tumor in extragonadal sites. This patient was treated with a combination of vincristine, actinomycin D, and cyclophosphamide, and concomitant cobalt irradiation. For endodermal sinus tumors in the pineal region, this combination appears more effective than previously reported treatment by irradiation alone.