This is an interesting case, in that the contrast appearance and homogeneity of the largest periventricular mass are quite good for CNS lymphoma, especially in the presence of low ADC values and high density on non-contrast CT, which implies high cellularity.
Presence of thalamic haemorrhage would be unusual for lymphoma however (unless immunocompromised). The differential is therefore essentially between a high grade glioma (GBM) or lymphoma. The location and appearance would be unusual for metastases. The high cellularity essentially excludes demyelination.
The patient went on to have a craniotomy.
MICROSCOPIC DESCRIPTION: The sections show features of a densely cellular astrocytic tumour. The tumour cells show elongated, angulated and hyperchromatic nuclei. Scattered large multinucleated tumour giant cells are noted. In some areas, the tumour cells have high N/C ratio with granular chromatin and nuclear moulding. They show patchy positivity for synaptophysin, consistent with PNET-like differentiation. Tumour cells are seen to extend into the cerebral cortex. Scattered mitotic figures are identified. There are foci of endothelial cell hyperplasia. Some of the blood vessels show perivascular lymphocytes. Areas of necrosis are present, some with pseudopalisading. The features are those of glioblastoma.
FINAL DIAGNOSIS: Glioblastoma (WHO Grade IV).