Sequential MRI findings in a patient with a germ cell tumor in the basal ganglia.

Serial changes of MRI scanning of an 11-year-old boy with hemiparesis due to a germ cell tumor in the basal ganglia are presented. Initial brain MRI T1-weighted images revealed a subtle mixed signal intensity lesion at left anterior and posterior limbs of the internal capsule. This lesion was not enhanced with Gd-DTPA, however, T2-weighted images showed a misty high signal intensity lesion in the same region. The MR images also showed hemiatrophy of the left basal ganglia. Histologic examination of biopsy specimens of the tumor revealed an embryonal carcinoma. The patient was treated with chemotherapy with subsequent improvement in the hemiparesis. Our case suggests that germ cell tumors must be considered in the differential disorders of lesions in the ipsilateral hemiatrophic basal ganglia in pediatric patients with hemiparesis.