Pituitary germinoma after resection of a mature third ventricular teratoma: illustrative case

Abstract

Background: Metachronous intracranial germ cell tumors (iGCTs)-unrelated, histologically different iGCTs occurring at different time points-occurring within the same patient remain a rarity. Herein, the authors report such a case and discuss the literature and potential pathophysiological mechanisms leading to this phenomenon.

Observations: A 9-year-old boy presented with new-onset impaired balance, headaches, nausea, visual disturbances, and left facial paresis. Magnetic resonance imaging (MRI) scans revealed a suspected pineal region teratoma originating from the pineal gland with consecutive obstructive hydrocephalus. A mature teratoma was diagnosed and resected. Postoperative recovery was good, and the patient could return to his normal daily activities. However, a new, slowly progressive lesion in the sellar region with an enlarged infundibular stalk was detected on follow-up MRI 3.5 years after initial pineal region teratoma resection. Biopsy revealed a newly developed pure germinoma. The patient was treated with radiotherapy plus chemotherapy and remained relapse free at the last follow-up. Sixteen other cases have reported a surgically resected primary mature teratoma, wherein patients developed metachronous germinomas during follow-up. Different theories try to elaborate this phenomenon, yet none can completely account for it.

Lessons: Although rare, metachronous iGCT is a phenomenon neurosurgeons should be aware of. In patients treated for iGCT, close long-term clinical, imaging, and laboratory follow-up is recommended. https://thejns.org/doi/10.3171/CASE2443.

Keywords: germ cell tumor; germinoma; mature teratoma; pediatric neurosurgery; pineal gland; pituitary.

FIG. 1.

A and B: Initial T2-weighted MRI showing the mature teratoma in the pineal region. C: Radiographic image showing dense structures (teeth) in the pineal gland. D: Three-dimensional reconstruction image of the teeth found in the pineal gland.

FIG. 2.

Intraoperative image of the pineal region teratoma before biopsy.

FIG. 3.

Sagittal postcontrast T1-weighted (A) and T2-weighted (B) MRI sequences showing thickening of the infundibulum as the first sign of tumor presence in the pituitary. Growth of the lesion prebiopsy on T1-weighted (C) and T2-weighted (D) MRI sequences.