A large mass lesion measuring distorts and displaces the middle and inferior frontal gyri on the right.
The lesion's epicentre is extra-axial in nature however regions of the signal abnormality are also identified within the cortex and the overlying white matter.
Compression of the right lateral ventricle is noted.
Thinning of the overlying diploic space is noted.
There is no associated contrast enhancement.
No raised cerebral blood volume.
No evidence of diffusion restriction.
The ADC is markedly elevated
MR spectroscopy at the periphery of the lesion demonstrates decreases in all metabolites.
Review of the preceding CT scan shows that the lesion is predominantly of the low attenuation. No evidence of fat or calcification
Conclusion: A large mass lesion predominantly extra-axial overlies the right frontal lobe. A definitive diagnosis is not reached. The heterogeneity of signal intensity as against arachnoid cyst. The elevated ADC is unusual for epidermoid. A neuroglial cyst is thought a more likely diagnosis. A primary intra-axial tumour is thought unlikely