Schnitzler syndrome, an autoimmune-autoinflammatory syndrome: report of two new cases and review of the literature.

Schnitzler syndrome is a rare disorder characterized clinically by chronic urticarial rash accompanied by fever, arthralgia or arthritis, bone pain and lymphoadenopathy and biochemically by monoclonal gammopathy and elevation of inflammatory indices. The disorder is very likely under-recognized and its origin remains obscure although it may be included among the immune mediated inflammatory diseases with features of autoinflammation and autoimmunity. We describe here two patients affected by Schnitzler syndrome, both refractory to corticosteroids and immunosuppressive therapy, successfully treated with the interleukin-1 receptor antagonist Anakinra. Unfortunately after two weeks, one patient experienced an important local adverse reaction to the biological drug. We decided to discontinue Anakinra with flare of the disease after 24 h. We therefore switched to Rituximab obtaining a complete remission in two months. We searched MEDLINE in order to analyze the frequency of the disease, its pathogenesis and outcome. The electronic search was conducted using the following key words "Schnitzler syndrome" and "Treatment of Schnitzler syndrome". All the selected papers, except the clinical reviews, described at least one case of Schnitzler syndrome. The review of the literature highlighted that Schnitzler syndrome remains an enigmatic disorder hard to categorize and to treat.