Presentation
B-cell acute lymphoblastic leukemia, on methotrexate therapy; presenting with headaches.
Patient Data
Coalescing T2-weighted hyperintense signal abnormalities involving the bilateral frontoparietal deep white matter and periventricular regions, with sparing of the subcortical U fibers. T2-weighted hyperintense signal abnormalities are also seen in the genu of the corpus callosum and in the bilateral cerebellar hemispheres. No restricted diffusion or enhancement.
Case Discussion
Methotrexate-related CNS toxicity may be seen as:
toxic leukoencephalopathy
disseminated necrotizing encephalopathy
subacute combined degeneration
Toxic leukoencephalopathy is the most common of the three and commonly presents within two weeks of administration, but may occur beyond this period. It appears as restricted diffusion and T2 hyperintense signals bilaterally across vascular territories, affecting the centrum semiovale and sparing the subcortical U fibers. The imaging findings are often transient but may persist after symptoms resolve.
Methotrexate-related CNS toxicity is more common among pediatric patients. Intrathecal administration has been reported as a risk factor.
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