Toxic leukoencephalopathy - methotrexate

Case contributed by Frank Gaillard
Diagnosis probable


Systemic malignancy

Patient Data

Age: Adult

Widespread involvement of the deep white matter (high T2 signal) without contrast enhancement or restricted diffusion. Note how the subcortical U-fibers are spared (best seen on FLAIR). 

Panda sign

Annotated image

Diffuse involvement of the white matter around the red-nuclei makes the red nuclei stand out mimicking a panda's face.  Superiorly, the subcortical U-fibers are spared (blue arrows).

Case Discussion

This patient received both intrathecal methotrexate and whole body (including cranial) irradiation. They then presented with gradual decrease in cognitive function.

Findings are thought to be consistent with a toxic leukoencephalopathy.

Intravenous methotrexate is associated with TL in 10% whereas it is seen in up to 40% of those who are treated by the intrathecal route.

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