Neural differentiation and maturation in metastatic medulloblastoma--case report.

A 6-year-old boy presented with a cerebellar medulloblastoma. Radical removal of the tumor and postoperative irradiation achieved complete remission. However, a metastatic tumor in the frontal lobe developed 2 years later. Radical removal and postoperative chemotherapy achieved partial remission, but he died of multiple intracranial and intraspinal dissemination of the tumor 2 years later. Comparison of the light microscopy, immunohistochemical staining, and electron microscopy findings from specimens of the tumors showed that the mainly undifferentiated primary tumor demonstrated both glial and neural differentiation, while the more mature metastatic tumor showed only neural differentiation. This suggests that differentiation and maturation of immature tumors such as medulloblastoma may proceed independently of metastatic potential.