Objective: The treatment of intracranial mixed germ cell tumors presents a unique challenge, since eradication of malignant tumor by radiation and/or chemotherapy may spare the benign tumor component. We reviewed our surgical experience with residual malignant pineal germ cell tumors after neoadjuvant therapy.
Methods: Between 1987 and 1997, 16 patients with malignant intracranial germ cell tumors were treated at the Mayo Clinic with a protocol of neoadjuvant chemotherapy and radiation therapy. After the diagnosis was confirmed by histopathological examination, all patients were treated with four cycles of etoposide and cisplatin as well as external beam radiation therapy (range, 3030-5940 cGy). Six patients had an incomplete response to therapy, as demonstrated by observation of residual tumor on magnetic resonance imaging scans. Initial pathology in these six patients was germinoma in four and combinations of yolk sac tumor, embryonal carcinoma, malignant teratoma, and germinoma in two. Two patients had synchronous pineal and suprasellar tumors, with leptomeningeal dissemination. Tumor markers were elevated in four of the six patients at presentation.
Results: All patients with residual pineal tumors underwent surgical resection via an infratentorial, supracerebellar approach. Pathological examination revealed mature teratoma in five patients and amorphous debris in one patient. No patient had recurrent malignancy. Significant neurological morbidity occurred in one patient, with no mortality. At a mean follow-up of 23 months, no recurrence on magnetic resonance imaging has been documented.
Conclusion: Residual pineal tumor occurring after treatment of malignant intracranial germ cell tumor with neoadjuvant therapy is likely to be mature teratoma. Operative resection of these benign recurrences is safe and effective.