Pineal Cystic Germinoma with Syncytiotrophoblastic Giant Cells Mimicking MR Imaging Findings of a Pineal Cyst

Summary: We report a case of precocious puberty in a 4-year-old boy. Contrast-enhanced T1-weighted MR imag-ing suggested a pineal cyst with enhancement of the slightly thickened wall and focal wall irregularity. Three-dimen-sional constructive interference in a steady-state imaging revealed a focal lobulation and a nodule-like area in the lesion. The lesion mimicking a pineal cyst proved to be a germinoma with syncytiotrophoblastic giant cells, on the basis of biopsy and tumor marker results. Primary pineal tumors are rare in all primary intra-cranial neoplasms, and most include germ cell tu-mors, pineal parenchymal tumors, and gliomas (1). Germ cell tumors are classified into six histologic types: germinoma, teratoma (mature and immature teratomas and teratoma with malignant transforma