A primary third ventricle mixed germ cell tumor with leptomeningeal dissemination of immature teratoma component.

A 17-year-old male patient presented to the clinic with a headache, nausea, and vomiting. Magnetic resonance imaging demonstrated a fat-containing and -enhancing heterogeneous tumor in the third ventricle, and fat droplets within the ventricles and the subarachnoid space. Obstructive hydrocephalus was also present. Emergency subtotal removal of the mass was performed via interhemispheric transcallosal approach. The histopathological diagnosis was a mixed germ cell tumor that was composed of embryonal carcinoma, yolk-sac tumor, germinoma, and immature teratoma containing a large amount of mature elements. The patient was referred for postoperative chemoradiotherapy. A mixed germ cell tumor is a rare type of nongerminomatous germ cell tumor that is made up of at least two different types of germ cell tumors. These may include germinoma, choriocarcinoma, embryonal carcinoma, yolk sac tumor, mature teratoma, immature teratoma, or teratoma with malignant degeneration. As far as we know, this is the first reported case of a primary third ventricle mixed germ cell tumor with leptomeningeal dissemination of the immature teratoma component that contains grossly visible mature elements at admission.