Glioblastoma developing from pleomorphic xanthoastrocytoma

A mass is demonstrated in the anterior pole of the left temporal lobe that has low intrinsic T1 signal and high T2 signal, with a surrounding cuff of elevated T2 signal consistent with vasogenic edema. The mass demonstrates heterogeneous, predominantly peripheral contrast enhancement and contains a focus of restricted diffusion.

A small "mass" demonstrated on the right side of the cerebral falx exhibits high T1 weighted signal, which disappears on fat saturated sequences probably represents ossification, rather than a small meningioma.

MICROSCOPIC DESCRIPTION:

The sections show a densely hypercellular glial tumor centered in  white matter and extending focally into overlying cortex. Tumor cells  are markedly pleomorphic with variably shaped, large vesicular nuclei,  many with conspicuous nucleoli. An occasional mitotic figure is  identified. No endothelial cell hyperplasia is seen and there is no  necrosis. Moderate numbers of tumor cells have foamy, xanthomatous  cytoplasm. Scattered multinucleated tumor giant cells are also  noted. Prominent perivascular cuffing by small lymphocytes is  noted in several areas of the tumor. Tumor cells, including those  with xanthomatous features, show strong immunostaining for GFAP and  nestin. The features are of pleomorphic xanthoastrocytoma (PXA). The  topoisomerase labeling index is approximately 5%. 

DIAGNOSIS:

Pleomorphic xanthoastrocytoma (PXA) - WHO Grade II.

Large heterogeneous T2 bright mass has grown in the temporal pole. Other sequences unfortunately not available. 

Paraffin sections show a densely hypercellular astrocytic glioma. Tumor cells are a mixture of pleomorphic spindle cells fibrillary astrocytes. The spindle cells 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. Tumor cells show strong immunostaining for GFAP and nestin. No areas with histological features of pleomorphic xanthoastrocytoma (PXA), as seen in the initial resection specimen are present in this tumor. The features are of glioblastoma. The topoisomerase proliferation index is approximately 12%.

DIAGNOSIS:

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

COMMENT:

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

Recurrent heterogeneous mass at the site of previous resection. 

MICROSCOPIC DESCRIPTION:

Paraffin sections show fragments of a densely hypercellular glial tumor. Tumor 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. Tumor cells have a diffuse sheeted and, in some areas, an intersecting vesicular arrangement. Frequent mitotic figures are identified and there is extensive tumor 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. 

DIAGNOSIS:

Glioblastoma (WHO Grade IV) developing from pleomorphic xanthoastrocytoma.