Our data indicate, that in addition to the histological and immunohistochemical evaluation, investigation of MGMT promoter methylation and in particular BRAFV600E mutations represent reliable additional tools to sustain differentiation of gcGBM from PXA on a molecular basis.
The BRAFV600E mutation occurs frequently in certain brain tumors such as pleomorphic xanthoastrocytoma, ganglioglioma, and pilocytic astrocytoma, and less frequently in epithelioid and giant cell glioblastoma.
We further investigated the utility of combined BRAFV600E (VE1) and p16 analysis by immunohistochemistry to distinguish PXAs from relevant histological mimics like giant-cell glioblastoma.
BRAFV600E mutation has been identified in up to 2/3 of pleomorphic xanthoastrocytomas (PXAs), World Health Organization grade II, as well as in varying percentages of PXAs with anaplastic features (PXA-A), gangliogliomas, extracerebellar pilocytic astrocytomas, and, rarely, giant cell glioblastoma multiforme (GC-GBMs).