Progressive multifocal leukoencephalopathy in idiopathic CD4+ lymphocytopenia: A case report and review of literature.

Progressive multifocal leukoencephalopathy (PML) is a rare demyelinating disease due to a lytic infection of oligodendrocytes caused by polyoma virus (JC virus) infection. PML usually occurs in a setting of severe immunosuppression and is most commonly associated with human immunodeficiency virus (HIV) infection. Idiopathic CD4+ lymphocytopenia is a very rare cause of PML and only a few cases have been reported in the literature. We present a case of a 45-year-old man who presented with behavioral alteration followed by progressive weakness of right side of the body. Contrast-enhanced magnetic resonance imaging of the brain revealed confluent irregular areas of T2-weighted/fluid-attenuated inversion recovery hyperintensities in left frontoparietal and right temporoparietal regions. His hematological work up showed a decreased absolute CD4+ count of 217 per microliter, but was negative for HIV serology. Keeping a differential diagnoses of central nervous system lymphoma, brain biopsy was performed. Histopathology revealed demyelination with presence of intranuclear inclusions in the oligodendrocytes, which were positive for SV40 immunostain. Adjacent areas showed reactive gliosis with hypertrophic astrocytes, hence a diagnosis of PML was made. The patient died due to aspiration pneumonia. PML can occur very rarely in association with idiopathic CD4+ lymphocytopenia in the absence of other immunosuppressive illnesses. This report highlights the importance of high index of clinical suspicion and need for a careful histological examination for diagnosis of PML to facilitate adequate patient management.