Best Post of December 2018: Giant cell GBM masquerading as an anaplastic PXA

The next in our "Best of the Month" series is from December 4, 2018:

At first glance, this tumor with pleomorphic cells and prominent perivascular lymphocytic cuffing strikes one as a pleomorphic xanthoastrocytoma (PXA).

The relative circumscription, as demonstrated by the stark difference in tumor burden in adjacent gyri depicted above also suggests the possibility of  PXA.

The presence of mitotic figures (center of picture above) and a small amount of necrosis and microvascular proliferation (not pictured) suggests the possibility of anaplastic PXA.

However, perivascular lymphocytes and relative circumscription can be seen in giant cell glioblastoma (GC-GBM). Pointing away from anaplastic PXA is the fact that there was no evidence of Rosenthal fibers and eosinophilic granular bodies. Additionally, there was strong p53 immunohistochemical positivity. The final diagnosis was Glioblastoma, IDH-wildtype, WHO grade IV, giant cell variant.