The authors report a rare case of a cortical ependymoma in a 10-year-old boy. The patient presented with complex partial seizures and a well-circumscribed, right frontal cortical mass. Routine microscopy showed a glial tumor with diverse histologic features. Immunohistochemistry and electron microscopy were required to establish the definitive diagnosis of cortical ependymoma. Cortical-based pediatric brain tumors range from World Health Organization grade I to III lesions and require significantly different treatment and follow-up. This case illustrates the importance of establishing an accurate neuropathologic tissue diagnosis of all pediatric cortical tumors. Copyright 2003 S. Karger AG, Basel