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Washington University Experience | MUSCLE | Myopathies with Mitochondrial Pathology | 21A2B (Case 21) Bicep Muscle-L_017 - Copy

The mitochondrial proliferation associates with a lipopigment granule. (electron micrographs) ---- Not shown: Gomori trichrome shows numerous ragged red fibers. PAS shows staining at the upper limit of normal in most of the section and occasional fibers have mildly increased staining. There is no storage material on Sudan. Cytochrome oxidase shows many fibers with reduced or absent staining, at least a few in each fascicle. SDH shows a comparable number of fibers with increased staining. ---- Interpretation: This is an abnormal muscle with multiple pathologies. First, there is evidence of a mitochondrial myopathy, a conclusion based on the ragged red and ragged blue fibers evident on Gomori trichrome and SDH, respectively, as well as the many fibers with reduced or absent staining on cytochrome oxidase. There are also features of myosin loss, which is commonly associated with clinical features of quadriparesis and respiratory failure, often in the setting of critical illness, and following exposure to corticosteroids and/or paralytics. Finally, there are changes consistent with ongoing and chronic partial denervation with reinnervation.

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