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Washington University Experience | MUSCLE | Myopathies with Mitochondrial Pathology | 6B3C Mitochondriopathy (Case 6) EM 014 - Copy

These mitochondria are enlarged, mostly round and somewhat pale, but do not contain inclusions or deposits of membrane. There are occasional lipid droplets adjacent to the mitochondria. (electron micrographs) ---- Not shown: COX stain highlights enlarged mitochondria but no fibers with reduced density of COX staining. SDH showed no muscle fibers with marked mitochondrial proliferation. PAS showed increased glycogen in muscle fibers. There is no lipid storage with Sudan stain. ---- Comment: This is an abnormal muscle biopsy suggestive of a mitochondrial disorder based on COX labeled large mitochondria and increased glycogen staining on PAS. However, mitochondrial oxidative enzyme activities show minimally increased SDH activity and normal COX activity.

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