Progressive Multifocal Leukoencephalopathy After Therapy for Chronic Lymphocytic Leukemia

Progressive multifocal leukoencephalopathy (PML) is a lethal degenerative disorder of the central nervous system caused by reactivation of latent polyomavirus JC in the immunosuppressed host. Although the condition is most prevalent among individuals with HIV, it also occurs in association with other diseases and therapies that compromise immune function, including lymphoproliferative disorders (LPDs) treated with chemotherapy. Herein, the clinical course of an individual with chronic lymphocytic leukemia who developed PML after treatment with fludarabine, cyclophosphamide, and rituximab is described. The report highlights diagnostic challenges posed by nonspecific neurologic symptoms and radiographic findings that can be associated with PML. The ensuing discussion describes important discoveries that have contributed to the understanding of PML, clinical and diagnostic characteristics of the disease, specific features of LPD-associated PML, and treatment strategies for this condition.