Fig. 9

Pembrolizumab-induced toxic leukoencephalopathy. A 72-year-old female with non-small cell lung carcinoma (NSCLC) had received Pembrolizumab (200 mg intravenous administered every 3 weeks). Three days after the second cycle of Pembrolizumab, she was admitted with sudden onset confusion, ataxia, and cognitive impairment. Axial FLAIR (a) and T2-weighted (b) MRI brain scans reveal hyperintensities in bilateral periventricular white matter and bilateral lentiform nuclei, external capsules, and claustrum (arrows). These findings are consistent with Pembrolizumab-induced toxic leukoencephalopathy. She was given high-dose methylprednisolone administered intravenously at 1000 mg daily for 3 days, with a near-complete resolution of his expressive dysphasia and improvement in gait. She was discharged on a regimen of 60 mg of prednisolone daily, which was subsequently weaned by 10 mg each week. A Follow-up MRI brain one month after discharge reveals a significant reduction of the T2 and FLAIR hyperintensities in the basal ganglia as demonstrated on axial FLAIR (c) and T2-weighted (d) images