PMC7655992_01
MRI scan. (a) Multiple enhancing corpus callosum lesions. (b, arrow) Partial open-ring pattern in the left occipital lobe and right periventricular lesion. (c, arrow) High signal on diffusion-weighted imaging. (d, arrow) Low values on ADC map. (e) Spontaneous regression five days after biopsy.
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F1
T1-weighted magnetic resonance (MR) imaging revealed that all the hyperdense lesions identified on CT were enhanced, in addition to newly identified lesions in the left occipital lobe and the midbrain, the latter of which was compressing the sylvian aqueduct. The lesion around the corpus callosum showed homogeneous enhancement [Figure 1a and b], with a high signal on diffusion-weighted imaging [Figure 1c] and a low apparent diffusion coefficient (ADC) value [Figure 1d]. The lesion in the left occipital lobe showed heterogeneous enhancement with a partial open-ring pattern and low ADC value [Figure 1b and d] which was chosen for a stereotactic biopsy due to its accessible nature and comparatively safer location. On the 5th day post-biopsy, repeated imaging showed significant regression of all the lesions without steroid therapy [Figure 1e].
First biopsy (a) H and E perivascular and parenchymal infiltration, (b) CD68-positive histiocytes, (c, arrowhead) CD8-positive reactive T-lymphocytes, (d, arrowhead). A small number of CD20- and (e, arrowhead) CD79a-positive B-lymphocytes. (f) Demyelinating lesions with Kluver-Barrera staining.
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F2
The histopathological report from this biopsy described perivascular and parenchymal lymphocytic infiltration with the presence of large diffuse astrocytes as well as foam cells, and evidence of astrogliosis [Figure 2a]. Further, immunostaining for macrophage-specific markers described an abundance of CD68-positive histiocytes [Figure 2b]; there were also abundant CD3-, CD4-, and CD8-positive reactive T-lymphocytes [Figure 2c] with a small number of CD20- and CD79a-positive B lymphocytes [Figures 2d and e, respectively] in the perivascular and/or parenchymal lesions. Kluver-Barrera (KB) staining showed a reduced uptake of staining, suggestive of demyelination [Figure 2f].
MRI three-months after biopsy. (a, arrowhead) Gliotic lesion from the first biopsy. (b) Progressive lesions around the corpus callosum. (c, arrow) Second biopsy site. (d, arrow) Low values on ADC map. (e) H and E staining showing atypical lymphoid cells. (f) CD20-positive B immunophenotype tumour cells.
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ADC value [Figure 3d]. An accessible lesion located within the ventricle on the contralateral hemisphere to the previous biopsy site was biopsied promptly through an endoscopic-guided approach. The histopathological report revealed diffuse lymphoid atypical cells [Figure 3e]. Immunostaining was positive for the B cell marker CD20 [Figure 3f].