MICROSCOPIC DESCRIPTION: The sections show features of a densely cellular astrocytic tumor. The tumor cells show elongated, angulated and hyperchromatic nuclei. Scattered mitotic figures are identified. There are foci of endothelial cell hyperplasia. Occasional small areas of palisaded necrosis are present.
The tumor cells are IDH-1 negative. The ki-67 proliferative index ranges from 2 to 15% and approximately up to 20% focally.
A dural tail sign is very well known and unfortunately is thought pathognomonic for meningiomas by many junior doctors, which is simply not true. Not only to many other extra-axial masses result in dural tails, but so do a number of intra-axial masses (e.g PXA) and in this case GBM.