Eosinophilic myositis: could it be an adult-onset dystrophy?

A 40-year-old woman presented with a 20 kg weight loss and asymmetrical hip and shoulder girdle muscle weakness; she had a raised serum creatine kinase and mild peripheral blood eosinophilia. There was no evidence of a parasitic infection or vasculitis. A muscle biopsy showed eosinophilic myositis. Following treatment with oral corticosteroid, methotrexate and intravenous immunoglobulin infusion, her weakness initially mildly improved and her serum creatine kinase reduced. However, despite continued immunosuppression her condition progressed over 3 years. The pattern of muscle weakness suggested a muscular dystrophy. Genetic testing confirmed heterozygous calpain mutations consistent with limb girdle muscular dystrophy type 2A.