Multiple periventricular and juxtacortical regions of globular T2 signal hyperintensity are identified in the right and left frontal lobes, and left paramedian parietal lobe, with smaller region of abnormality in a subcortical location in the left posterolateral temporal lobe and another lesion centred on the right middle cerebellar peduncle. The periventricular lesions involve the anterior aspect of the corpus callosum body. Lesions are almost entirely T2 hypointense, although 2 of the right frontal periventricular lesions contain small central focus of hyperintensity. Supratentorial lesions demonstrate solid rather than peripheral or 'leading-edge' enhancement, while the right cerebellar peduncle lesion has blotchy peripheral enhancement. There is no low ADC diffusion restriction associated with the lesions. No subependymal or leptomeningeal enhancement is identified. No hydrocephalus. MR angiogram demonstrates no intracranial stenosis or occlusion. There is no vessel wall irregularity.
Conclusion: The morphology of these globular periventricular, subcortical and cerebellar peduncle T2 hyperintense lesions raises the possibility primary CNS lymphoma. Demyelination (acute disseminated encephalomyelitis) is also a consideration although open-ring peripheral enhancement is usually seen.