Table of Contents

Washington University Experience | MUSCLE | Myopathies with Mitochondrial Pathology | 33A1 (Case 33) EM043 - Copy

Case 33 History ---- The patient is a 75-year-old man with a history of symmetric proximal weakness, ophthalmoplegia, profound asymmetric facial and bulbar weakness resulting in dysphagia and dyspnea, and elevated GDF15, concerning for mitochondrial myopathy/CPEO, who presents for follow-up. Electrodiagnostic testing showed a non-irritable myopathy. Serum showed no autoantibodies and a normal NfL. Genetic testing showed a single pathogenic intronic variant in GAA and a PLEC VUS. Operative procedure: Left deltoid muscle biopsy. ---- 33A1-7 Ultrastructural examination showed several mitochondrial abnormalities in this case. There were numerous fibers which demonstrated the accumulation of large groups of small mitochondria in a subsarcolemmal distribution and, in smaller groups, between the sarcomeres. Individual mitochondria varied significantly in size and shape, some were branched and accumulated in small groups within the interior of the muscle fiber. In a few fibers inter-sarcomeric mitochondria were smaller than normal mitochondria and, in some regions, appeared to be absent entirely. In a subpopulation of fibers mitochondria contained paracrystalline “parking lots”, internal structure within long cylindrical forms and in cross sections. (electron micrographs)

---