PMC3114618_01
An MRI scan with T2-weighting and with fluid-attenuated inversion recovery (a-c) obtained at the time of initial presentation shows a hyperintense lesion in the deep white matter of the left temporal lobe (a) and several lesions in the subcortical, deep and periventricular white matter of the parieto-occipital region bilaterally (b, c). These lesions were mainly confined to the white matter as shown by the relative sparing of the cortex and were not enhanced by the administration of gadolinium on T1-weighted MRI (d-f). Arrowheads: hypointense lesions corresponding to the lesions in a, b and c, respectively.
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F1
T2-weighting and fluid-attenuated inversion recovery (fig. 1) obtained at presentation revealed a hyperintense lesion in the deep white matter of the left temporal lobe and several hyperintense lesions in the subcortical, deep and periventricular white matter of the parieto-occipital region bilaterally. The lesions were mainly confined to the white matter with relative sparing of the cortex.
Follow-up MRI scan two weeks after initial presentation revealed a slight increase in size of lesions in the parieto-occipital region (comparison with fig. 1). However, no new lesions were noted anywhere. A gadolinium-enhanced T1-weighted MRI revealed that the non-enhancing lesions were better delineated (d-f). Arrowheads: hypointense lesions corresponding to the lesions in a, b and c, respectively.
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F2
An MRI scan of the brain revealed a slight increase in the size of the lesions in the parieto-occipital regions although no new lesions were noticed (fig. 2).
Histologic and electron microscopic findings of PML. Hematoxylin and eosin-stained section of the right parietal lobe (a, b) showing shows diffuse astrocytosis (a, original magnification x200) with many of the astrocytes containing large, irregular nuclei (arrows). Occasionally, a smudgy type of material was observed within their nuclei (inset shows a magnified view of astrocytes with enlarged nuclei, original magnification x400). Oligodendroglial cells were sparse and enlarged and contained ground glass inclusions (b, arrows, original magnification x200) (inset shows the magnified image of an oligodendrocyte with viral inclusion body in the nucleus, original magnification x400). Conventional electron microscopy images of astrocytes from a stereotactic biopsy of the right parietal lobe showing enlarged and irregular nuclei (c, original magnification x8,000, and d, original magnification x15,000). The nuclei exhibit focal loss of nuclear envelope (NE) (arrowheads) while viral particles are observed attached to the nuclear membrane in clusters (e, original magnification x60,000). Higher magnification reveals numerous icosahedral 35-45 nm viral particles within the astrocyte nucleus (f, original magnification x300,000). C = Cytoplasm; N = nucleus; NE = nuclear envelope.
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F3
Hematoxylin and eosin staining (fig. 3) revealed diffuse astrocytosis with many of the astrocytes containing large, irregular nuclei.