The Effect of Intravenous Methylprednisolone on Recurrent Exacerbation in Hematologic Malignancy-associated Progressive Multifocal Leukoencephalopathy

We herein report a 65-year-old man with progressive multifocal leukoencephalopathy (PML) after 2-year remission from acute myeloid leukemia who developed recurrent episodes of left hemiparesis with gadolinium enhancement on magnetic resonance imaging. Steroid pulse therapy for each exacerbation induced clinical and radiological improvement, suggesting that exacerbations are an excessive immune response to the JC virus and distinct from immune reconstitution inflammatory syndrome (IRIS). Although glucocorticoids are recommended only for IRIS, steroid pulse therapy should be considered as a therapeutic option in cases of exacerbation of hematologic malignancy-associated PML. Importantly, neuroimaging is not sufficient to differentiate excessive inflammation from a controlled inflammatory response, for which steroids are not recommended.