Contiguous malignant astrocytoma and Wilms'-like tumor in the brain.

A case of primary brain tumor composed of two contiguous neoplasms in presented. At operation, a nodular tumor was embedded in the infiltrating tumor within the brain parenchyma. With light and electron microscopy, the nodular tumor was similar to Wilms' tumor (nephroblastoma). The infiltrating tumor was malignant astrocytoma. Autopsy revealed, besides the recurrence of malignant astrocytoma in the brain and its subarachnoid dissemination, extracranial metastases to the abdominal cavity, liver, lung, and bone marrow. Recurrent and metastatic tumors were glioblastoma multiforme, which was more malignant than the surgical specimen. The possibility of metastatic Wilms' tumor from the kidney was completely ruled out by extensive autopsy survey. The authors present an extremely rare tumor including detailed observations on the electron microscopic appearance of the tumor; the histogenesis of these tumors is briefly discussed.