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Washington University Experience | MUSCLE | Target Fibers | 1J7C (Case 1 EM049 - Copy

Higher magnification of image #1J7A. (electron micrograph) ---- Interpretation: This is an abnormal muscle with a combination of multiple pathologies. There are changes in muscle compatible with the inflammatory vasculopathy/vasculitis. There are findings of ongoing and chronic vasculitic neuropathy resulting in denervation with reinnervation. Ongoing denervation is evidenced by the small fibers with darker staining on NADH and esterase and the presence of many fibers with targets and/or targetoid changes. Evidence of chronic denervation with reinnervation includes the abnormal variation in fiber size with pyknotic nuclear clumps and hypertrophied fibers, fibers with internal nuclei, increased endomysial connective tissue, replacement of connective by fat, and fiber type grouping.

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