Association of pleomorphic xanthoastrocytoma with cortical dysplasia and neuronal tumors. A report of three cases.
BACKGROUND: Several recent publications indicate that pleomorphic xanthoastrocytoma (PXA) may occasionally express ganglionic cell differentiation, linking this type of tumor to other benign, mixed glioneuronal neoplasms. Furthermore, ganglionic tumors and less frequently some benign glial tumors in the central nervous system, could be associated with a variety of mild developmental abnormalities of the cerebral cortex that are classified under the broad term cortical dysplasia. The association of cortical dysplasia with PXA and a neuronal pattern of differentiation has not been reported previously. METHODS: The authors present clinical, radiologic, immunohistochemical, and ultrastructural findings in three patients with cortical dysplasia. The cortical dysplasia was continuous with PXA, displaying an additional component of neuronal cell differentiation. RESULTS: The ages of the patients were 23, 47, and 52 years. Resection of the tumors was predated by temporal lobe seizures by 6 years in 1 patient and by more than 30 years in the others. In all 3 cases, radiologic studies conducted 3-6 years before surgery showed either no abnormality or lesions that were initially nonprogressing. CONCLUSIONS: The longstanding clinical history of seizures and the existence of radiologically documented dormant lesions several years before tumor removal both suggest that PXA in these patients very likely developed in benign hamartomatous cortical lesions or in preexisting cortical dysplasia. The authors' findings, along with the consistent occurrence of PXA in the gray matter in the majority of the reported cases, indicate that these tumors may originate either from a subclass of astrocytes histogenetically and topographically associated with neurons or from multipotential neuroectodermal precursor cells common to neurons and astrocytes.