[A case of progressive multifocal leukoencephalopathy with chronic renal failure, whose JC virus in cerebrospinal fluid disappeared after mefloquine-mirtazapine dual therapy].

An 83-year-old man with chronic renal failure was referred to our hospital because of subacute progressive right hemiparesis. A brain MRI showed high-intensity lesions in bilateral middle cerebellar peduncles and white matter of the left frontal lobe on T2-weighted images. The lesions increased gradually, so we suspected a brain tumor because 1H-MRS images showed elevated Cho and decreased NAA, and also pathologic findings of the brain biopsy suggested glioblastoma. However, JC virus (JCV) in cerebrospinal fluid was revealed highly positive by PCR. So we reconsidered pathologically and finally found bizarre astrocytes which were infected with JCV in immunohistochemical studies and we diagnosed progressive multifocal leukoencephalopathy at last. Then we medicated with mefloquine and mirtazapine, and the JCV in cerebrospinal fluid disappeared, without new MRI lesions. This is a rare case in respect of the background of the patient and the clinical course.