Glioblastoma developing from pleomorphic xanthoastrocytoma

Paraffin sections show a densely hypercellular astrocytic glioma.Tumour Tumour cells are a mixture of pleomorphic spindle cells fibrillaryastrocytes. The spindle cells are are arranged in loose fasciculiwhile the fibrillary astrocytes have a diffuse sheeted and focallyorganoid arrangement. Frequent mitotic figures are identified andthere are scattered foci of vascular endothelial cell hyperplasia.There There is extensive necrosis. Tumour cells show strong immunostainingfor GFAP and nestin. No areas with histological features ofpleomorphic xanthoastrocytoma (PXA), as seen in the initial resectionspecimen of 2009, are present in this tumour. Thefeatures are of glioblastoma multiforme. The topoisomeraseproliferation index is approximately 12%.

DIAGNOSIS:

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

COMMENT:

Comparison of the histological features of the initial tumour with with the recurrent tumour indicates that the recurrencerepresents malignant transformation in a pleomorphicxanthoastrocytoma. No anaplastic features are identified in theinitial tumour with the histological features being typical of a WHOGrade 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 multiforme developing from pleomorphic xanthoastrocytoma and are similar to those seen in the specimen of 2010.

DIAGNOSIS:

Glioblastoma multiforme (WHO Grade IV) developing from pleomorphic xanthoastrocytoma.