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Washington University Experience | MUSCLE | Myopathies with Mitochondrial Pathology | 36A1 (Case 36) Cervical Paraspinal_012 - Copy

Both cervical paraspinal muscle and deltoid muscles were biopsied in this case. There is no evidence of inflammation or vasculitis in either. There were no nemaline rods encountered. ---- 36A1-4 Paraspinous muscle: This muscle had a definitive ultrastructural phenotype characterized by significantly increased numbers of mitochondria, both in a subsarcolemmal distribution and deeper within the fiber in smaller clumps. Mitochondria were enlarged, had unusual lengths and angular shapes, varying from fiber to fiber, containing dark coarse cristae and numerous associated lipid droplets. A subpopulation of muscle fibers additionally contained autophagosomes, some containing mitochondria but most with smaller granular debris. There were numerous large lipopigment (lipofuscin) granules with clear lipidic and osmiophilic constituents; some of these structures had a curvilinear appearance but those inclusions were rare. Some dilated vacuoles appeared to belong to the T-tubule system. Rare small vessels contained vacuolar and solid cytosomes. In some fibers there were increased amounts of granular debris with admixed tubulovesicular elements. There is no storage material on Sudan or PAS. SDH and cytochrome oxidase show irregular internal architecture in many fibers but no primary mitochondrial pathology.

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