Glioblastoma developing from pleomorphic xanthoastrocytoma

A 14x12x13 mm mass is demonstrated in the anterior pole of the left temporal lobe.

This lesion that has low intrinsic T1 signal and high T2 signal, with a surrounding cuff of elevated T2 signal consistent with vasogenic oedema.

The mass demonstrates heterogeneous, predominantly peripheral contrast enhancement and contains a focus of restricted diffusion.

No other parenchymal abnormality is demonstrated.

A 6 x 20 mm convexsmall "mass" demonstrated on the right side of the cerebral falx exhibits high T1 weighted signal, which disappears on fat saturated sequences.

No hydrocephalus is present.Conclusion

Mass demonstrated in the inferior pole of the left temporal lobe is consistent with stated history of GBM; in the right clinical context, a cerebral abscess and cerebritis could also give this appearance, although this is thought less likely.

Small right sided falcine extra axial mass is probably falxrepresents ossification, rather than a small meningioma, of unlikely clinical significance.

Paraffin sections show a densely hypercellular astrocytic glioma. Tumour cells are a mixture of pleomorphic spindle cells fibrillary astrocytes. The spindle cells are are arranged in loose fasciculi while the fibrillary astrocytes have a diffuse sheeted and focally organoid arrangement. Frequent mitotic figures are identified and there are scattered foci of vascular endothelial cell hyperplasia. There is extensive necrosis. Tumour cells show strong immunostaining for GFAP and nestin. No areas with histological features of pleomorphic xanthoastrocytoma (PXA), as seen in the initial resection specimen of 2009, are present in this tumour. The features are of glioblastoma. The topoisomerase proliferation index is approximately 12%.

DIAGNOSIS:

Recurrent left temporal lobe tumour: Glioblastoma (WHO Grade IV)

COMMENT:

Comparison of the histological features of the initial tumour with the recurrent tumour indicates that the recurrence represents a malignant transformation in a pleomorphic xanthoastrocytoma. No anaplastic features are identified in the initial tumour with the histological features being typical of a WHO Grade II pleomorphic xanthoastrocytoma.

MICROSCOPIC DESCRIPTION:

Paraffin sections show fragments of a densely hypercellular glial tumour. Tumour cells are a mixture of large cells with markedly pleomorphic vesicular nuclei and a large amount of foamy cytoplasm, mixed with smaller cells with round, oval and angulated vesicular nuclei and fibrillary processes. Tumour cells have a diffuse sheeted and, in some areas, an intersecting vesicular arrangement. Frequent mitotic figures are identified and there is extensive tumour necrosis incorporating necrotic blood vessels. The overall features are of glioblastoma developing from pleomorphic xanthoastrocytoma and are similar to those seen in the second specimen of 2010.

DIAGNOSIS:

Glioblastoma (WHO Grade IV) developing from pleomorphic xanthoastrocytoma.