Primary Yolk Sac Tumor in the Cerebellar Vermis. Case Report

A 2-year-old boy presented with gait disturbance and limb ataxia. T1 weighted magnetic resonance (MR) imaging with gadolinium diethylenetriaminepenta-acetic acid administration showed a heterogeneously enhanced mass lesion with a cystic component in the cerebellar vermis. The minimum apparent diffusion coefficient value of the lesion was 1.96 x 10(3) mm(2)/sec, and H MR spectroscopy showed elevated choline and lipid peaks, and decreased N-acetyl asparate peak. The tumor was totally resected, and the histological diagnosis was yold sac tumor. Consistent with this diagnosis, a fetoprotein levels in the serum and cerebrospinal fluid were 7,094 ng/m/ and 22.3 ng/m/ respectively. F-18-fluorodeoxyglucose positrions emission tomography and thoracic abdominal and pelvic computed tomography showed no abnormal lesions, excluding the possibility of metastatic yold sac tumor from an extracanial lesion. The patient received chemotherapy consisting of ifosfamide, cisplatin and etoposide and had not relapsed at 6 months after resection. Germ cell tumors rarely develop in the postenor fossa. This case suggests that yolk sac tumor could develop in the cerebellar vermis.