The patient went on to have a resection.
Tumor cells have regular round and oval vesicular nuclei, many with discernible nucleoli and delicate processes. Aggregates of nuclei are separated by fibrillary eosinophilic neuropil-like material. No mitotic figures are identified and there is no vascular endothelial cell proliferation or necrosis.
Tumor cells show strong peri-nuclear granular immunostaining for synaptophysin. No staining for epithelial membrane antigen (EMA) or GFAP is seen in tumor cells and there is no nuclear staining for Ki-67/MIB-1. The features are of central neurocytoma.
Final diagnosis: central neurocytoma.