[Intravenous immunoglobulins in the treatment of polymyositis and dermatomyositis].

Polymyositis and dermatomyositis are two inflammatory muscle diseases of unknown origin mediated by a dysimmune mechanism via a cytotoxic effect against the muscle fiber in polymyositis and a humoral effect against the muscle vessels in dermatomyositis. First line treatment of polymyositis and dermatomyositis is still based on corticosteroid therapy. In case of failure, corticosteroid dependence, or intolerance, a second line treatment using immunosuppressors or polyvalent human intravenous immunoglobulins (IVIg) is usually associated. We report our experience with IVIg in the treatment of 50 patients with myositis unresponsive to corticosteroids and immunosuppressors. Thirty-five patients had polymyositis and 15 had dermatomyositis. We discuss the possible mechanisms and their precise role in the therapeutic armamentarium in these dysimmune diseases.