Progressive multifocal leukoencephalopathy (PML) is a demyelinating disease of the
central nervous system caused by a lytic infection of oligodendrocytes due to the
presence of JC polyomavirus (JCV). The disease occurs mostly in immunocompromised
patients and is associated with a high mortality rate. The diagnosis of PML is based
on a polymerase chain reaction (PCR) assay for JC viral DNA in cerebrospinal fluid
(CSF). However, case reports of the diagnosis of PML established with brain biopsy
despite negative JCV CSF PCR analysis when clinical and neuroimaging features are
suggestive of PML have been published. A 44-year-old male with a 6-year history of
acquired immunodeficiency syndrome developed mental confusion and memory impairment
despite 3 months of highly active antiretroviral therapy. Magnetic resonance imaging
revealed multiple subcortical white matter lesions in bilateral hemispheres and subcortical
nuclei including the thalamus and basal ganglia. JCV DNA was not detected in CSF study,
but a brain biopsy showed a high JCV DNA titer. The diagnosis of PML was established
with brain biopsy. An early brain biopsy may be important in the diagnosis of PML
in patients with clinical manifestations and neuroimaging findings if JCV DNA is undetectable
in the CSF PCR.
Key-words:
Acquired immunodeficiency syndrome - brain biopsy - demyelination - DNA test - human
immunodeficiency virus - JC virus - progressive multifocal leukoencephalopathy