Cortical ependymoma with unusual histologic features.

Cortical ependymomas are rare gliomas with classic ependymal features but are unusual in primarily involving the cerebral cortex. Here, we present a 19-year old woman with new-onset seizures who was found to have a large, cortically based non-enhancing lesion with scalloping of the overlying calvarium. Abundant ependymal features were present including classic ependymal cytology, diffuse GFAP and dot-like EMA positivity, and well developed cilia, microvilli, and intercellular junctions on ultrastructural analysis. Additionally, the tumor showed areas of infiltrative growth similar to angiocentric glioma as well as striking mucin-filled microcystic spaces somewhat reminiscent of myxopapillary ependymoma. Thus far, the patient shows no evidence of recurrence following gross total resection. This case demonstrates detailed morphologic, immunohistochemical, and ultrastructural evidence supporting a relationship between cortical ependymoma and angiocentric glioma and suggesting that cortical ependymomas can have myxopapillary as well as classic features.