Progressive multifocal leukoencephalopathy

Case contributed by RMH Neuropathology


Right lower limbs weakness and clumsiness, increased slurred speech and acute episode of right lower limb spasm. CT code stroke was unremarkable.

Patient Data

Age: 75
Gender: Male

MRI Brain


Pre and post contrast T1 sequences with perfusion and spectroscopy performed to complete characterization of the cortical and subcortical T2 hyperintensity in the left posterior frontal lobe and involving pre and postcentral gyrus.

This demonstrated nonspecific smooth thin dural enhancement, but no parenchymal or leptomeningeal enhancement.

Although morphologic appearance of signal change could be explained by subacute ischemia, the absence of gyriform enhancement and the clinical history of onset would be quite unusual.

MR spectroscopy has a wandering baseline, but there is no large lactate peak.

The postcentral gyrus signal change also extends slightly further medially than is typical for MCA territory.No perfusion abnormality identified.

Conclusion: There are several features which cast doubt on a diagnosis of subacute ischemia, with the main alternative differential being low grade glioma.

A follow-up MRI in 4 to 6 weeks would be helpful to look for temporal evolution.

The patient underwent to a brain biopsy. New MRI was requested after the confirmed histopathology results due to a progressive right lower limb weakness. 

MRI Brain


Interval left parietal burr hole. There has been slight progression of the FLAIR hyperintensity within the left pre- and postcentral gyri, left middle frontal gyrus and posterior left superior frontal gyrus, with slightly increased mass effect. FLAIR hyperintensity within the medial left occipital lobe has also slightly progressed. Increased DWI signal on ADC measurement appears to be T2 shine through.

No enhancement within the regions of FLAIR abnormality. Smooth thin pachymeningeal enhancement is again demonstrated bilaterally. No brainstem abnormality demonstrated.

Periventricular and deep white matter foci of FLAIR hyperintensity are again demonstrated, consistent with moderate chronic small vessel ischemic change.

Conclusion: Mild progression of the FLAIR hyperintensity and mass effect within the left frontal, parietal and occipital lobes. No brainstem abnormality.

MICROSCOPIC DESCRIPTION: 1&2. Sections show a piece of neural tissue composed of grey and white matter. At one edge of the biopsy the white matter demonstrates aggregates of foamy macrophages, enlarged hyperchromatic reactive astrocytes and oligodendroglial ground glass intranuclear inclusions.

Immunohistochemical results confirm positive staining for SV40/BK virus, consistent with JC virus infection.

DIAGNOSIS: Brain, left parietal lesion: JC virus infection (progressive multifocal leukoencephalopathy).

Case Discussion

Progressive multifocal leukoencephalopathy is a demyelinating disease which results from the JC virus infecting oligodendrocytes. It is considered the most common clinical manifestation of JC virus infection in the brain.

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