Female, 38 years old, with history of tongue cancer status post chemotherapy, last MRI concerning for toxicity due to 5-FU. A repeat MRI to assess for worsening or improvement. Diffusion restriction seen previously within the splenium of the corpus callosum and the bilateral thalami has resolved. No new areas of restricted diffusion are demonstrated.There is minimal residual FLAIR hyperintensity within the splenium at the site of the prior lesion. No definite residual signal abnormality is seen in the thalami. T2 hyperintensity within the pons has, however, become more coalescent and homogeneous.No evidence of intracranial hemorrhage or any large extra-axial fluid collection is seen. The previously suspected thin bilateral subdural effusions have improved with minimal residual fluid and/or dural thickening. The ventricular system is normal in size and morphology.
Interval resolution of restricted diffusion is seen involving the splenium of the corpus callosum in the bilateral thalami. There is minimal residual FLAIR signal abnormality within the splenium. T2 hyperintense signal abnormality within the pons has become more coalescent and homogeneous.This pattern of abnormalities has been reported as a rare consequence of 5-FU exposure. Other potential considerations including an infectious encephalitis, metabolic derangement, or osmotic demyelination are probably less likely.