Brain MRI of patient with rituximab-associated progressive multifocal leukoencephalopathy (PML) in the left frontal lobe

A 65-year-old patient developed PML while being treated with rituximab. Axial FLAIR MRI shows subcortical white matter hyperintensity involving the premotor area of left frontal lobe. As is typical for most lesions of PML, there is sparing of the more superficial cortex on MRI.