Fig. 3

Histopathologic findings of brain at autopsy. Paraffin-embedded sections of the grossly solid lesions stained with Luxol fast blue / hematoxylin and eosin (LFB/H&E) demonstrated a central core of macrophage infiltration (black arrow), a rim of demyelinated axons (white arrow), and a clear demarcation from the myelinated white matter a LFB staining of the white matter adjacent to the cavitary lesions demonstrated conspicuous myelin preservation of the overlying subcortical U-fibers b and preservation of axons by neurofilament staining c In the areas of macrophage infiltration, there was evidence of myelin within macrophages on LFB (inset) d, preservation of axons by neurofilament staining e, and the macrophages were positive for CD163 f. Lymphocytic inflammation was scarce in the lesions, with only scattered parenchymal and perivascular CD3 + T-lymphocytes g H&E-stained sections of the spinal cord at all levels showed similar lesions with prominent involvement of the dorsal columns and sparing of corticospinal tracts h Ultrastructural analysis of cortical neurons did not identify definitive abnormal mitochondria (i). Size bars are 100 μm (panels a-g), 1 mm (panel h), and 600 nm (panel i)