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Washington University Experience | MUSCLE | Myopathies with Mitochondrial Pathology | 20A1 (Case 20) EM072 - Copy
Case 20 History ---- The patient is a 1-year-old boy presenting for evaluation for a mitochondrial disorder consisting of esophageal stricture, congenital hypotonia, possible arthrogryposis, and some dysphagia with a de novo mutation in KMT2C. EMG and nerve conductions are normal. ACHR antibodies are normal. Brain MRI shows large ventricles. Serum CK level is 282.Operative procedure: Muscle biopsy, right thigh. ---- 20A1-6 There were numerous subsarcolemmal and intraparenchymal collections of mitochondria in significant numbers. Individual mitochondria were large, up to 5-10 or more times the normal diameter, with abnormal cristae which were more tubular and diffuse. Within individual enlarged mitochondria a few cristae developed patchy osmiophilia. Small lipid droplets were intimately associated with abnormal mitochondria or collections of mitochondria. A number of fibers had subsarcolemmal collections of free glycogen granules, often as an admixture of glycogen with abnormal mitochondria. A few poorly preserved collections of debris appeared to contain autophagosomes with mitophagy. There were no intramitochondrial "parking lots", ring mitochondria or matrix dense granules which may be seen in mitochondrial myopathy.
