Vasculitic Tibial Mononeuropathy Associated with Inherited Immune Dysregulation: A Review of Tibial Mononeuropathies with Electrodiagnostic Considerations

Figure 1

Right sural nerve biopsy. (a) Hematoxylin and eosin staining shows a small caliber vessel in the perineurium surrounded and focally invaded by mononuclear cells, indicative of active ongoing vasculitis. On the top left corner, the longitudinal section of the nerve with significant paucity of myelinated axons. (b) MOVAT pentachrome staining shows several degenerating axons (purple globules), indicative of active ongoing axonopathy; in addition, there is a significant loss of myelinated axons with secondary endoneurial fibrosis (pale-tan material around remaining myelinated axons). (c) Double immunostaining CD3 (brown) smooth muscle actin (red) shows several T cells surrounding, focally invading, and disrupting the vessel wall. (d) CD20 shows admixed B cells. Inset shows the cross section of a reanalyzed vessel indicative of remote, healed vascular injury.

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