The patient went on to have a resection.
Histology
Sections show a circumscribed low-grade glial-neuronal neoplasm located within white matter, with focal extension into cortex. The lesion is characterized by microcystic spaces associated with intervening threads of glial tissue and aggregates of oligodendroglial-like cells. Floating neurons are evident. The lesion extends to an excisional margin.
FINAL DIAGNOSIS: Dysembryoplastic neuroepithelial tumor (DNET).