Progressive Multifocal Leukoencephalopathy in the Setting of Immune Reconstitution Syndrome

JC virus-associated progressive multifocal leukoencephalopathy (PML) continues to be an important cause of opportunistic infections in patients infected with human immunodeficiency virus (HIV). Here, we report a case of a 25-year-old man with a 2-year history of untreated HIV infection who presented with left hand weakness. After the initiation of highly active retroviral therapy, his viral load decreased, but his left-sided neurologic symptoms worsened. Findings from magnetic resonance imaging were consistent with PML, but no JC virus was detected in the central nervous system. The patient underwent brain biopsy, which revealed JC virus infection and changes associated with PML. This case illustrates the histopathologic findings in PML-immune reconstitution inflammatory syndrome, the phenomenon of paradoxical worsening of PML after initiation of HIV antiretroviral therapy, and highlights the limitations of JC virus detection in the cerebrospinal fluid for diagnosis.