Chordoid glioma of the third ventricle: confirmatory report of a new entity.

The term "chordoid glioma" was recently introduced to denote a circumscribed, apparently low-grade neoplasm arising in or preferentially involving the third ventricle of middle-aged women. We report biopsy and postmortem findings in a 60-year-old woman with symptoms of forgetfulness, headache, and lethargy. Neuroimaging showed a contrast-enhancing third ventricular mass with obstructive hydrocephalus. The tumor was subtotally resected. Microscopically, it consisted of clusters and strands of epithelioid cells in a mucoid matrix. Its margins were remarkably discrete and showed little tendency to infiltrate surrounding brain parenchyma. The majority of neoplastic cells were glial fibrillary acidic protein (GFAP) and vimentin positive, whereas S100 protein labeled only individual cells. Stains for epithelial membrane antigen (EMA) and cytokeratin were nonreactive. There was no evidence of neuroendocrine differentiation or expression of estrogen and progesteron receptors. Lymphoplasmacellular infiltrates were noted throughout the lesion and at the tumor-brain interface. The MIB-1 labeling index averaged 1.5%. At present, chordoid glioma is considered a glial neoplasm of uncertain histogenesis with distinct clinicopathologic features.