AB039. Malignant transformation of intracranial germinoma to non-germinomatous germ cell tumors—incidence, treatment strategy and outcome: a case report and literature review

Background: Intracranial germ cell tumors are rare neoplasms seen mainly in children and adolescents. Compared to non-germinomatous germ cell tumors (NGGCTs), germinomas typically respond well to chemo-radiotherapy and portend a better prognosis. We report here a patient with intracranial germinoma which showed complete remission following chemo-radiotherapy but re-presented with malignant transformation to NGGCT thirteen years later. We then performed a literature review to understand the treatment strategy and outcome of this rare phenomenon.

Methods: Review of the patient’s case note, followed by a literature review of the topic.

Results: A 13-year-old male presented with 6 weeks of polyuria and polydipsia. Imaging showed bifocal (suprasellar and pineal) lesions. Histology from an open biopsy diagnosed a germinoma. He underwent extended whole ventricular irradiation with local boost and chemotherapy, which led to complete resolution on imaging. Thirteen years later, he re-presented with headaches and diabetes insipidus. Imaging showed a new right frontal lesion with elevated serum beta-human chorionic gonadotropin (β-hCG) and alpha-fetoprotein (AFP). The tumor was excised with histology confirming a mixed tumor comprising germinoma, yolk sac, and choriocarcinoma. A literature review returned eight case reports of malignant transformation of intracranial germinoma to NGGCTs, covering eight patients (seven males, and one female; aged 5–23 years old). Four had the primary tumor located in the pineal region, three in the suprasellar region, and one at both sites. Recurrence with malignant transformation occurred at a median of 24.5 months after initial diagnosis (range, 5 months to 14 years). Five patients had recurrences intra-abdominally, all of whom had a ventriculoperitoneal shunt (VPS) inserted during the treatment of the initial tumor. Of the remaining three intracranial recurrences, two were at the same site while one at a distant site. The most common histology was yolk sac tumor (five patients), followed by two each of immature teratoma, choriocarcinoma, and embryonal carcinoma (some were mixed germ cell tumors). Of those with intra-abdominal recurrence, four died within 2 months of diagnosis. Those with intracranial recurrences survived longer, with a median survival of 15 months, and one longer than 27 months.

Conclusions: Malignant transformation to NGGCTs is rare. Relapse can occur intracranially, or in cases where VPS was present, intraabdominally. Outcomes following transformation were poor despite aggressive treatment, with those intra-abdominal recurrences faring much worse.

Keywords: Intracranial germinoma; germ cell tumor; malignant transformation