Progressive multifocal leukoencephalopathy (PML)

Case contributed by Frank Gaillard


Progressive left upper and lower limb weakness over 2 months. Known to be HIV positive on antiretroviral therapy (ART).

Patient Data

Age: 35 years
Gender: Male

CT of the brain demonstares a large area of low attenuation in the right hemisphere, without evidence of contrast enhancement. It affects the white matter, sparing the cortex. 

MRI brain - 3 days later


Extensive right frontoparietal white matter signal abnormality is seen traversing the posterior body of the corpus callosum to involve the left centrum semiovale and precentral gyrus. The abnormality extends to involve the subcortical white matter (subcortical U-fibers are involved) but spares the cortex. There is also increased inferior extent on the right, through the posterior limb internal capsule to the cerebral peduncle.  Signal abnormality also extends just into the occipital and posterior temporal lobes on the right. This is associated with no mass effect or abnormal enhancement.  Leading edge of diffusion restriction is present medially. Signal abnormality is all confluent with no new discrete lesion seen. No evidence of hemorrhage.

The patient went on to have the usual barrage of tests, confirming him to have high viral loads of JC virus, consistent with the diagnosis of PML.  

  •  Polyomavirus DNA by PCR:  DETECTED
    • BK Viral Load:677,000 Copies/mL
    • JC Viral Load: 4,367,500 Copies/mL
  • CRYPTOCOCCAL SEROLOGY: Specimen type - Serum and CSF - Cryptococcal Ag: NOT Detected
    • Lymphocytes    161
    • The smears contain increased numbers of lymphocytes. No malignant cells are identified.
    • Total WCC      30.50 x10^9/L  (normal = 4.00-11.00)
    • Total Lymph     0.30 x10^9/L  (normal = 1.20-4.00)
    • % CD3          32.90 %
    • Total CD3       0.10 x10^9/L  (normal = 0.70-3.58)
    • % CD4           2.30 %
    • Total CD4       0.01 x10^9/L  (normal = 0.35-2.63)
    • % CD8          28.80 %
    • Total CD8       0.09 x10^9/L  (normal = 0.12-1.47)
    • CD4:CD8         0.08 1.00-2.40
    • HIV-1 RNA by RT-PCR :   DETECTED
    • HIV-1 RNA Load :   <150       RNA copies/mL plasm
    • COMMENT:  This result has been obtained using the Abbott Real Time HIV-1 Assay.  This amplifies all Group M, N and O subtypes. The reliable limit of detection for the assay is 150-10,000,000 RNA copies/ml.

Case Discussion

This case demonstrates typical appearances of progressive multifocal leukoencephalopathy (PML) in a patient on antiretroviral therapy (ART) for HIV. 

It should be noted that this patient also has a high titer of BK virus, a relative of JC virus but not implicated in PML.

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