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Washington University Experience | MUSCLE | Autophagic myopathy | 8A Mito (Case 8) EM 1
Case 8 History ---- The patient is an 18-month-old girl with hypertrophic cardiomyopathy diagnosed at the age of six months, right optic nerve hypoplasia with an associated right-sided decreased visual field, an isolated seizure history, and mild hypotonia; she is otherwise developmentally normal. Her family history is significant for paternal male relatives with an unclear heart condition. Laboratory studies are significant for mildly elevated serum creatine kinase, elevated serum transaminases, elevated serum ammonia, elevated serum aldolase, and mildly elevated serum pyruvate. Serum amino acids, lactic acid and glycosylation are otherwise normal, as is plasma acylcarnitine. Operative procedure: Left quadriceps muscle biopsy. ---- Electron microscopic examination of the muscle tissue shows intermyofibrillar deposits of glycogen within a subset of muscle fibers. A smaller subset of fibers shows centrally-located deposits of osmiophilic lipidic/lysosomal debris. Morphologically abnormal or supernumerary mitochondria are not identified. ---- Not shown: H&E shows vacuolar changes in many muscle fibers in the biopsy. In most muscle fibers, the vacuoles are small with relatively well defined rims but occasionally are scattered throughout the biopsy in numerous muscle fibers, there are larger vacuoles that contain irregular variably stained debris and occasional nuclei. There is no inflammation. Acid phosphatase highlights staining of granules in many muscle fibers. ---- NM Division Impression: Vacuolar myopathy. The changes, including the sizes and distribution of the vacuoles, the presence of acid phosphatase positive granules and the appearance of increased glycogen within muscle fibers would be consistent with a glycogen storage disease, especially acid maltase deficiency. Biochemical measurements shows increased glycogen [156 μg/mg protein; nl 0.015]
