Glioblastoma IDH wild-type (with dural tail)

The patient went on to have a craniotomy and excision.

Histology

MACROSCOPIC DESCRIPTION:

An irregular piece of soft tan and dark brown tissue 30x28x11mm with an attached triangular sheet of rubbery tan dura 55x40mm. 

MICROSCOPIC DESCRIPTION:

Paraffin sections show a densely hypercellular astrocytic glioma. Tumour cells have predominantly fibrillary features and show moderate nuclear and cellular pleomorphism. Frequent mitotic figures are identified. There is microvascular proliferation and areas of both palisaded and confluent necrosis are also seen. Many of these incorporate thin-walled necrotic and thrombosed blood vessels.

Tumour extends along overlying dura from which it is variably separated by a layer of hyperplastic arachnoidal cells.

IMMUNOHISTOCHEMISTRY:

• GFAP positive
• Nestin positive
• IDH-1 R132H negative (not mutated)
• MGMT negative (likely methylated)
• p16 negative
• p53 negative
• Topoisomerase labelling index: Approximately 30%

FINAL DIAGNOSIS: A Glioblastomaglioblastoma (WHO Grade IV)

Discussion was histologically diagnosed. 

For some reason residents / registrars and clinicians are really hung up on the dural tail sign. They seem to feel that it is pathognomonic of an extra-axial mass. Well this is simply not the case and cortical lesions can induce dural thickening and thus a dural tail. In addition to GBM (this case), metastases and other primary tumours (e.g. PXA) can result in this appearance, as well as peripherally located infections.