Progressive multifocal leukoencephalopathy following rituximab treatment in a patient with rheumatoid arthritis.

Progressive multifocal leukoencephalopathy (PML) is a rare brain disease caused by reactivation of the JC virus. Herein, a case of PML in association with rituximab treatment in a patient with chronic rheumatoid arthritis (RA) and Sjögren's syndrome is described. The patient received 4 courses of rituximab (2 1,000-mg infusions administered 2 weeks apart) over a period of approximately 40 months, during a phase III trial and safety extension study. PML was diagnosed approximately 18 months after the last rituximab course, and the patient died 1 month later. Determination of the cause of PML was confounded by the fact that the patient had developed oropharyngeal cancer, which was treated with chemoradiotherapy, 9 months prior to the development of PML. Although there was no direct evidence that linked rituximab to the development of PML, this case highlights the need to consider a diagnosis of PML in patients with RA who have been treated with rituximab and who subsequently develop new neurologic symptoms.