[Precocious puberty caused by hCG-producing germinoma involving the bilateral basal ganglia and cerebral white matter without 1ypical radiologic findings: case report].

An 8-year-old boy presented with a rare case of germinoma involving the bilateral basal ganglia and cerebral white matter manifesting as precocious puberty. Magnetic resonance (MR) imaging at the initial presentation demonstrated mild hyperintense areas in the bilateral basal ganglia and corpus callosum on T1-weighted images, and a small hyperintense spot in the right internal capsule on T2-weighted images. Human chorionic gonadotropin (hCG) level was elevated in the cerebrospinal fluid (CSF), so we strongly suspected that threre was a hCG-producing germinoma originating in the bilateral basal ganglia. Stereotactic biopsy was performed. Histological examination revealed two-cell pattern germinoma. After three cycles of combination chemotherapy consisting of ifosfamide, cisplatin, and etoposide, followed by whole brain irradiation with a total dose of 24 Gy, the CSF hCG level fell below the detection limit, but MR imaging demonstrated no significant change. Intracranial hCG-producing germinoma should be suspected in patients presenting with precocious puberty and elevated CSF hCG level. Moreover, slight intensity change on MR imaging is important to identify germinoma arising from the basal ganglia in the early stage.