FIG. 4.

Patterns of encephalitis and myelitis distal to visible PCs. H&E. Scale bars=50 μM. (A) Neuron cell bodies (in the reticular formation, here) appear to be targeted by inflammation, primarily composed of presumptive microglial cells. While some neurons undergoing neuronophagia appear degenerate (chromatolysis, pyknosis, shrunken, and hypereosinophilic; black arrowheads) many neurons that appear completely healthy are surrounded by presumptive microglial cells (black arrows). (B) Inflammation in the spinal cord (myelitis) is characterized primarily by presumptive microglial cells admixed with occasional lymphocytes. Multifocally, there may be individual necrotic neurons (white arrows) characterized by a shrunken, angular profile, karyolysis, and severe hypereosinophilia.