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Washington University Experience | MUSCLE | Atrophy, muscle cell, NOS | 16A1 Atrophy-hypertrophy (Case 16) 2

Case 16 History ---- The patient is a 6-year old boy with a one-year history of progressive, asymmetric, bilateral muscle weakness, with preserved reflexes and an intact sensory examination, growth retardation, frequent symptoms consistent with upper respiratory infection, and enlarged tonsils. Serum creatine kinase is mildly elevated. Clinical diagnosis: Rule out myopathy. Operative procedure: Left quadriceps muscle biopsy. ---- 16A1,2 Microscopic examination of the left quadriceps muscle biopsy material shows striated muscle fibers with fatty infiltration, extensive fiber size variation, and multifocal lymphocytic vascular cuffing. The majority of fibers exhibit severe atrophy with a concordant increase in the number of syncytial knots and are found in large groups. Multi-layered cuffs of small, benign appearing lymphocytes are associated with multiple small vessels within the muscle but lack definitive angionecrosis. (H&E)

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