The patient went on to have a resection. 

Histology

The sections show multiple fragments of a tumor which shows areas of necrosis and foci of microcalcification.   The tumor consists of sheets of regular rounded cells with round nuclei. Chromatin is speckled or vesicular and small nucleoli are often seen.   In places,  the nuclei surround small rounded eosinophilic areas resembling neuropil.  There is also a minor pattern of perivascular pseudorosetting.  The mitotic count is elevated at up to 5/10 hpf.  There is focal microvascular proliferation.

Immunohistochemical stains show positive staining for synaptophysin and NeuN.  The Ki67  stain shows areas of the tumor with up to 15% of nuclei staining.

The features are those of a central neurocytoma.   However, the increased proliferative activity,  with microvascular proliferation and areas of necrosis  suggest that the lesion is best regarded as an atypical neurocytoma. A higher chance of recurrence could be anticipated.​