Glioblastoma IDH wild-type (with dural enhancement)
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Centered on the posterior temporal and parietal regions of the left hemisphere is heterogeneous mass which is predominantly intra-axial, involving cortex, with contrast enhancement extending to the ependymal surface of left lateral ventricle. It is associated with very extensive increased T2 signal, and exerting significant local mass effect and midline shift.
Some of the contrast enhancing component of this mass abuts the pia, with prominent leptomeningeal vessels in the region, and a large cortical vein displaced by a partially cystic extra-axial component. Some of these regions demonstrated pachymeningeal dural tails. Further regions of wispy contrast enhancement are seen in the inferior most aspect of the left temporal pole, and possibly deep to the cortex of the cingulate gyrus anteriorly on the left.
MR spectroscopy, although not of great quality (not shown), suggest moderate elevation of choline and depletion of NAA adjacent to the enhancing component is with some increase in the lactate also seen more centrally.
The enhancing component demonstrates elevation of cerebral blood volume (CBV) (not shown).
Appearances are somewhat atypical, but extension of contrast enhancing tissue to the ependymal surface, and MR spectroscopy and would favor a high grade primary brain tumor (GBM). Extra-axial component, temporal location, in an elderly male also raises the possibility of a gliosarcoma, albeit these are rare.
Leptomeningeal metastatic disease and a malignant meningioma could have similar appearances but are thought significantly less likely, especially in the absence of known metastatic disease.
The patient went on to have surgery.
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.
FINAL DIAGNOSIS: Glioblastoma (WHO Grade IV).
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.