A case of polymyositis positive for the serum anti-SRP antibody that was successfully treated with intravenous immunoglobulin therapy

Abstract

    The idiopathic inflammatory myopathies are systemic autoimmune diseases characterized by chronic inflammation, leading to progressive weakness of the proximal muscles. Myositis-specific or associated autoantibodies are often found in the serum of polymyositis (PM) and dermatomyositis patients. Anti-SRP (signal recognition particle) antibody is thought to be associated with severe forms of the disease, particularly those with heart and lung involvement and resistant to adrenocorticosteroids. We present a66-year-old female polymyositis patient with serious muscle weakness and high CPK level (21550IU/L). Despite initial therapy with high-dose methylprednisolone (1g/day x3days,i.v.) followed by prednisolone (1mg/kg/day,p.o.) plus cyclosporine A (150mg/day), muscle weakness was not improved and CPK levels were not reduced to less than3000IU/L. After treatment with intravenous immunoglobulin (IVIG), muscle strength was gradually improved and CPK levels were reduced to less than700IU/L. To our knowledge, there were few reports that PM positive for serum anti-SRP antibody treated with IVIG. IVIG might be a therapeutic agent of choice for steroid-resistant cases of serum anti-SRP antibody-positive PM.