Longitudinal study of two cases of progressive multifocal leukoencephalopathy with a clinical benign evolution.

Progressive multifocal leukoencephalopathy (PML) usually is a rapid and fatal demyelinating disease of the central nervous system (CNS), caused by JC virus (JCV). After the introduction of Highly active antiretroviral therapy (HAART), its prognosis has been modified in some cases but remains a relevant cause of morbidity in human immunodeficiency virus-seropositive (HIV+) patients. The authors report here two cases of PML, followed over time, sharing a benign course and a JCV antigen-specific T-cell response, but with different cerebrospinal fluid (CSF), magnetic resonance imaging (MRI), and clinical features. In both cases, JCV DNA detection in brain biopsies samples and specific antigenic response preceded its isolation in the CSF by several months. In one patient, during the first stage of the disease, the presence of CSF and MRI inflammatory findings, associated with the lack of JCV detection in the CSF, made the diagnosis more challenging. Given that to date a reformation of the laboratory parameters for PML diagnosis is strongly needed, this report highlights the following considerations: (a) indications for performing brain biopsy in HIV-related leukoencephalopathies of uncertain origin, and (b) the role of JCV immunologically specific T-cell response as an additional marker for PML diagnosis and indicator for good prognosis of the disease.