Adult-Onset Mixed Germ Cell Tumor Composed Mainly of Yolk Sac Tumor Around the Pineal Gland: A Case Report and Review of the Literature

Background Mixed germ cell tumors (MGCTs) usually occur in children. In the present report, we discuss an extremely rare case of adult-onset MGCT composed mainly of yolk sac tumor (YST) around the pineal gland. Case Description A 54-year-old Japanese man presented with disturbance of consciousness, Parinaud's syndrome, and gait disturbance. Magnetic resonance imaging revealed a pineal mass lesion, and subtotal resection of the tumor was achieved. The histologic diagnosis was MGCT, consisting mainly of YST. Although he underwent 5 courses of chemotherapy and craniospinal irradiation after surgery, tumor dissemination could not be controlled, and he died 10 months postoperatively. Conclusion The present case highlights the need for clinicians to include YST in the differential diagnosis of acute progressive lesions around the pineal region, even in adult patients.