Simultaneous intracranial and testicular germ cell tumors: illustrative case.

backgroundSimultaneous intracranial and testicular germ cell tumors (GCTs) are extremely rare, leading to a lack of adequate experience in their treatment. Therefore, the authors report a case of this kind of GCT. OBSERVATIONS: A 5-year-old boy was admitted to the hospital with headache and vomiting. Computed tomography and magnetic resonance imaging suggested the possibility of a GCT in the pineal region. The value of the serum tumor marker alpha-fetoprotein (AFP) was 5,396.1 μg/L, and β-human chorionic gonadotropin levels were within the normal range. Subsequently, the tumor was removed, and the final pathological result was a mixed GCT. Therefore, chemotherapy and radiation were added. However, the authors found a testicular tumor on ultrasound at the same time, and pathology after surgery suggested a mature cystic teratoma. Following treatment, the patient recovered well, and AFP levels dropped to normal values. LESSONS: To the authors' knowledge, this report is the fourth case of simultaneous intracranial and testicular GCTs and the first case of a simultaneous mixed GCT in the pineal region and mature teratoma of the testis. A combination of surgery, chemotherapy, and radiation therapy for mixed GCTs in the pineal region and surgical excision for testicular reproductive cell tumors are effective in these patients, but long-term monitoring is required.