The patient went on to have debulking. 

Histology

MICROSCOPIC DESCRIPTION: All the sections show a densely cellular astrocytic tumor. The astrocytes form sheets. Most of these cells are gemistocytes with enlarged hyperchromatic nuclei and moderate amounts of eosinophilic cytoplasm. Scattered mitoses are seen. There are occasional foci of mild endothelial cell hyperplasia. Necrosis is absent. Perivascular lymphocytes are seen. There is tumor involving the cerebral cortex. The features are those of anaplastic astrocytoma of the gemistocytic type (gemistocytic astrocytoma). IDH-1 immunostain is positive. The Ki-67 index is about 8%.

DIAGNOSIS: Anaplastic gemistocytic astrocytoma  (WHO grade III).

Discussion

This is a fairly typical appearance for a gemistocytic astrocytoma, with little difference in appearance between WHO Grade II and Grade III lesions on imaging. Both tend to be large tumors, most commonly located in the frontal lobes, with areas of non-enhancement, partial suppression on FLAIR, cystic change and enhancement. 

The differential is really only of a WHO grade IV lesions, GBM.