Bilateral metachronous germinoma of the basal ganglia occurring long after total removal of a mature pineal teratoma: Case report

OBJECTIVE AND IMPORTANCE: We report the extremely rare occurrence of a second germ cell tumor at a different site and with different histological types long after total removal of a mature pineal teratoma. CLINICAL PRESENTATION: A 10-year-old boy who presented with headache and vomiting was admitted to our hospital. Neuroradiological studies revealed a tumor in the pineal region. The tumor was totally removed. Histologically, the tumor proved to be a mature teratoma. The patient's postoperative course was uneventful. The patient received no adjuvant therapy and was followed in the outpatient clinic. Three years later, he was readmitted with transient left upper limb weakness and vomiting. Neuroradiological studies showed a tumor in the bilateral basal ganglia. INTERVENTION: The second tumor, which was located in the right basal ganglion, was partially removed for biopsy. Histologically, the tumor proved to be a germinoma. The patient received three cycles of combination chemotherapy consisting of carboplatin and etoposide with radiotherapy. After the second course of chemotherapy, magnetic resonance imaging studies revealed no evidence of the tumor. CONCLUSION: The second tumor was considered to be a de novo metachronous neoplasm rather than a recurrence of the original mature teratoma. We think that if primordial germ cell groups exist along the midline of the brain, more than two primordial germ cell groups could give rise to metachronous neoplasms at different sites and with different histological types.