The patient went on to have surgery.

Histology:

Paraffin sections show a moderately hypercellular ependymoma. Tumor cells have mildly pleomorphic round and oval nuclei with a pepper and salt chromatin arrangement and are arranged in well-formed peri-vascular pseudo-rosettes. An occasional ependymal canal is identified. Scattered mitotic figures are identified. No vascular endothelial cell hyperplasia is seen and there is no necrosis. No evidence of invasion into brain parenchyma is seen. Focal calcification is noted.

FINAL DIAGNOSIS: posterior fossa ependymoma. WHO Grade 2

Note: as molecular profiling was not carried out in this case, it would have the diagnosis of posterior fossa ependymoma not otherwise specified (NOS).