Fig. 1.

Brain MRI and biopsy histological findings.

(A) Brain MRI before treatment. High-intensity signals on FLAIR were observed in the white matter of the temporal and occipital lobes, hippocampus, amygdala, and occipital cortex in the left top and bottom: A Gd contrast-enhanced radial perivascular lesion from enhanced ventricle walls, the ependyma in the choroid plexus, and meninges in the right top and bottom.

(B) Spinal cord MRI revealed a long cord lesion in the central gray matter with a hazy pattern of Gd enhancement (Fig. 1B).

(C) Head MRI after treatment. FLAIR image in the upper panel. Gd enhancement was not observed on T1WI in the lower panel.

(D to H) Brain biopsy findings.

Perivascular lymphocytic infiltration (hematoxylin and eosin staining) (D) with CD20- (E) and CD3-positivive lymphocytes (F). Infiltration of CD8-positive lymphocytes into the brain parenchyma (G). Patchy disappearance of GFAP immunoreactivity in perivascular infiltration sites (H).