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Washington University Experience | MUSCLE | Myopathies with Mitochondrial Pathology | 12A2 Mitochondrial Myopathy (Case 12) EM 1 - Copy
Examination of the muscle biopsy material shows mitochondrial abnormalities including parking lot inclusions in a subset of muscle fibers. (electron micrograph) ---- Not shown: Gomori trichrome shows numerous ragged red muscle fibers scattered throughout the muscle biopsy. SDH suggests mitochondrial proliferation. Cytochrome oxidase shows numerous muscle fibers with reduced staining but only a few of which are truly COX negative. Most of the SDH positive muscle fibers have at least some COX staining, occasionally reaching normal levels. A Sudan stain highlights increased numbers of large lipid droplets throughout the biopsy. ---- Comment: The patient was diagnosed with mitochondrial myopathy manifest by numerous muscle fibers with mitochondrial proliferation scattered throughout the biopsy. SDH positive muscle fibers have at least some COX activity. The neuromuscular workup suggests this particular pattern may be seen in MELAS and related disorders. It is also present in muscle with some mtDNA deletions that do not include COX genes. Mitochondrial oxidative enzyme activities were normal.
