A Case of Schnitzler's Syndrome without Monoclonal Gammopathy-Associated Chronic Urticaria Treated with Anakinra.

Chronic urticaria may often be associated with interleukin (IL)-1-mediated autoinflammatory disease, which should be suspected if systemic inflammation signs are present. Here, we report a case of Schnitzler's syndrome without monoclonal gammopathy treated successfully with the IL-1 receptor antagonist anakinra. A 69-year-old man suffered from a pruritic urticarial rash for 12 years. It became aggravated episodically and was accompanied by high fever, arthralgia, leukocytosis, and an elevated C-reactive protein and erythrocyte sedimentation rate. The episodes each lasted for over one week. Neutrophilic and eosinophilic inflammation was found on skin biopsy. However, serum and urine electrophoresis showed no evidence of monoclonal gammopathy. The cutaneous lesions were unresponsive to various kinds of anti-histamines, systemic glucocorticoids, colchicine, cyclosporine, dapsone, and methotrexate, which were administered over a span of 3 years immediately preceding successful treatment. A dramatic response, however, was observed after a daily administration of anakinra. This observation suggests that the correct diagnosis of this case is Schnitzler's syndrome without monoclonal gammopathy. For an adult patient with refractory chronic urticaria and systemic inflammation, Schnitzler's syndrome could be considered as a possible differential diagnosis. Although the typical form of Schnitzler's syndrome exhibits the presence of monoclonal gammopathy as a diagnostic criterion, monoclonal gammopathy may be absent in an atypical form. In such a situation, an IL-1 antagonist should be effective for the management of chronic urticaria.