LAUSR

Dear Editor, Progressive multifocal leukoencephalopathy (PML) is a severe demyelinating disease of the central nervous system (CNS), fatal in some cases, and JC virus (JCV) is the usual cause [1]. BK virus (BKV) is a ubiquitous virus and its primary infection is generally asymptomatic. It occurs in childhood [2] and, as well as JCV, belongs to the Polyomaviridae family. Both viruses are associated with a clinical disease in the setting of immunosuppression: JCV commonly in association with PML, while BKV with nephropathy and hemorrhagic cystitis [2]. Here we report a rare case of BKV-associated PML in a patient with systemic lupus erythematosus (SLE).