The patient went on to have a biopsy which confirmed the diagnosis of GBM. 

Pathology

MICROSCOPIC DESCRIPTION: The sections show fragments of cerebral cortex and white matter with reactive changes. In addition, however, there are fragments of a densely hypercellular astrocytic glioma. Within these fragments, tumor cells show marked nuclear and cellular pleomorphism. Frequent mitotic figures are identified and there are prominent foci of endothelial cell hyperplasia. Both palisaded and confluent necrosis are also identified. Some of these areas of necrosis include thin walled necrotic and thrombosed blood vessels. The features are of glioblastoma.

DIAGNOSIS: Glioblastoma (WHO Grade IV).

Note: IDH mutation status is not provided in this case and according to the current (2016) WHO classification of CNS tumors, this tumor would, therefore, be designated as a glioblastoma NOS. 

Case discussion by Frank Gaillard, consultant neuroradiologist, Royal Melbourne Hospital.