Glioblastoma and a synchronous olfactory groove meningioma
MRI requested for known benign frontal tumour.
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There is a vividly enhancing extra-axial mass seen in the region of the olfactory grooves, measuring 3.8 x 3.2 x 2.0 cm. It has characteristic features of a meningioma. Posteriorly the mass extends over the entirety of the planum sphenoidale and a tongue of tumour creeps into the anterior aspect of the pituitary fossa. The optic nerves pass below the mass posteriorly into the optic nerve canals without in extension into the canal or orbit.
An intra-axial ill-defined 4 x 3 cm mass of the right parietal lobe is noted, consisting of high T2 signal involving cortex and subjacent white matter, ill-defined multifocal regions of enhancement. The enhancing component demonstrates restricted diffusion (ADC 750 x 10-6 mm2/s). No convincing macroscopic necrosis.
This patient has had the resection of both tumours in different times.
MICROSCOPIC DESCRIPTION: 1&2. Paraffin sections show a moderately hypercellular meningioma. This has a well developed syncytial architecture. Tumour cells have uniform nuclear features. No mitotic figures are identified.
There is a single small focus of infarct-like necrosis. No evidence of brain invasion is seen. Broad dural attachment is noted.
MICROSCOPIC DESCRIPTION: 1,2. The sections show features of a densely cellular astrocytic tumour. Most of the tumour cells have high N/C ratio with enlarged pleomorphic and hyperchromatic nuclei, granular chromatin, focal nuclear moulding and scanty cytoplasm. Many mitotic figures are identified. There are no foci of microvascular proliferation. Small areas of somewhat palisaded necrosis are present. The tumour cells are GFAP and nestin positive. They have focal synaptophysin and B-tubulin positive, consistent with PNET-like differentiation. The Ki-67 index is about 75%. They are IDH-1, MGMT, ATRX, NeuN, CAM5.2, CD20 and CD3 negative. The features are those of glioblastoma with PNET-like component.
DIAGNOSIS: 1,2. Brain tumour: Glioblastoma with PNET-like component (WHO Grade IV).