[Ineffective mefloquine therapy in progressive multifocal leukoencephalopathy complicated with malignant lymphoma: finding and usefulness of susceptibility-weighted imaging].

A 57-year-old woman presented with motor and cognitive impairments under treatment for cryptogenic organizing pneumonia with immunosuppressive agents. Magnetic resonance imaging showed widespread signal abnormalities in the cerebral white matter. Susceptibility-weighted imaging showed attenuated contrast of the cerebral medullary vein in the lesions, and (18)F-fluorodeoxyglucose-positron emission tomography ((18)F-FDG-PET) revealed decreased uptake at the same site and increased uptake in multifocal lung involvements. Lung biopsy findings were consistent with diffuse large B-cell lymphoma. Polymerase chain reaction for JC Virus DNA in cerebrospinal fluid yielded positive results. Based on these findings, the present case was given a diagnosis of progressive multifocal leukoencephalopathy (PML). The patient was treated with oral mefloquine, but her respiratory condition deteriorated and chemotherapy was required to prevent further deterioration. As a result, chemotherapy to treat lymphoma could not result in beneficial immune reconstitution, PML continued to progress despite mefloquine treatment, and the patient developed decorticate posture. The efficacy of mefloquine in patients with non-HIV-associated PML warrants further investigation.