[Progressive multifocal leukoencephalopathy after rituximab therapy in a patient with mantle cell lymphoma].

A 74-year-old man, who had mantle cell lymphoma treated with several anticancer drugs including rituximab, was admitted to our hospital because of gait disturbance and progressive paralysis of the right lower limb. T2-weighted MR image showed multiple high intensity lesions in the left parietal lobe. Suspected of being cerebral invasion of lymphoma, high-dose methotrexate was begun, but the patient died of sepsis without neurological improvement. At autopsy, it was proven that neurological symptoms had been caused by progressive multifocal leukoencephalopathy (PML). PML should be considered as a possible complication of heavily treated lymphoma.