Inflammatory changes in affected muscles of facioscapulohumeral dystrophy

A 34-year-old man developed slowly progressive muscular wasting of facioscapulohumeral (FSH) distribution with marked asymmetry. Clinical features, family history and laboratory findings were consistent with the diagnosis of FSH dystrophy. However, muscle biopsy revealed an inflammatory reaction with perivascular and endomysial infiltrate, myophagocytosis and invasion of the fibres by mononuclear cells. Monoclonal antibody analysis of the phenotypes of cells in the biopsy specimen suggested that cell-mediated immune response may occur during muscle fibre injury in FSH dystrophy.