Dysembryoplastic neuroepithelial tumor (DNET)
The patient went on to have a resection.
Sections show brain tissue, including cerebral cortex and white matter, with areas of a relatively localized and superficial low-grade glial tumor. The tumor cells are fibrillar, and in areas display a bipolar appearance. There is a propensity for perivascular localization with nuclear-free zones between vessels. Mitotic activity is not increased. Vascular neurogenesis is not seen. Necrosis is not evident. Some areas display a loose hypocellular and cystic background. Small microcystic areas are also focally evident. Individual tumor cells are round to oval-shaped, and elongated, depending on the orientation. Some granular bodies are seen. Floating neurons are not well-defined, although entrapped neurons are observed within several parts of the tumor. In some areas, the pattern of architectural arrangement of neurons is irregular, consistent with focal cortical dysplasia. A ganglion cell component of a ganglioglioma is not definitively excluded.
FINAL DIAGNOSIS: dysembryoplastic neuroepithelial tumor (DNET).