MRI
Large heterogeneous intra-axial mass involving grey and white matter (but with extensive cortical involvement) occupies the entire right temporal lobe, including the mesial temporal lobe and extends into the insula, right basal ganglia, right frontal operculum, right parietal, and right occipital lobes.
The lesion is predominantly FLAIR hyperintense with regions of susceptibility-related signal loss consistent with calcification on the phase component of SWI. Many of these areas demonstrate intrinsic high T1 signal. Taking this into account there is minimal if any whispy contrast enhancement. No nodular contrast enhancing component.
Marked elevation of relative cerebral blood volume within the lesion. Marked elevation of choline with depression of NAA in the lesion.
There is marked mass effect with diffuse sulcal effacement in the right hemisphere, and almost complete effacement of the right lateral ventricle with midline shift obstructing the outflow of the left lateral ventricle at the level of the foramen of munro. There is prominent left-sided transependymal oedema.
The right uncus, which is also expanded by tumour, herniates medially and compresses the midbrain.
Conclusion:
Features are those of an adult-type diffuse glioma. On imaging grounds alone it most likely represents an oligodendroglioma although it should be noted that IDH mutations are uncommon in this age group.