B-cell lymphoma in AIDS is the only other disease that likes to cross the corpus callosum. The only thing left is the leptomeningeal surface. This is called liquefactive necrosis with a cavitary infarct. It should not be mistaken for an abscess since an abscess has walls. This specimen is also characterized to have an OLD infarct because all the tissue was removed.
Macrophages literally remove the tissue.
There are NO fibroblastic scars, but a thin border of astrocytes and their processes remain. The middle cerebral vasculature supplies the area that was infarcted. This specimen has a herniation of a low-grade tumor going across the midline into the cingulate gyrus. The other possibility could have been edema, but edema is characterized by a chronic induration in the white matter. At the subdural surface, note the thickened neo-membrane dura.