BACKGROUNDS

The most important diagnostic criteria for Schnitzler syndrome include chronic urticaria, the presence of monoclonal IgM immunoglobulin, marked inflammation (leukocytosis, elevated CRP and erythrocyte sedimentation rate), subfebrile temperatures or fevers and bone and joint pains. It is a rare idiopathic disease that may lead to potentially life-threatening complications such as development of secondary amyloidosis or transformation into malignant lymphoproliferation. Schnitzler syndrome should be included in differential diagnostics of chronic urticaria and fevers of unknown origin. The diagnostic algorithm is based on clinical presentation and serum and urine electrophoreses to detect monoclonal components. Blockade of interleukin-1 (IL-1), key cytokine in the pathogenesis of the disease, dominates current therapeutic protocols. Anakinra (Kineret), recombinant human IL-1 receptor antagonist, is the most widely used treatment option. According to literature, disease remission was obtained in all treated patients. Therefore, anakinra represents a significant diagnostic possibility to differentiate Schnitzler syndrome from e.g. monoclonal gammopathy of unknown significance (MGUS) associated with urticaria of different aetiology. Biological therapy with rilonacept (Arcalyst) and canakinumab (Ilaris) represents a new treatment alternative for patients, allowing prolonged dosing intervals of 1 and 8 weeks, respectively (compared to 24 hours with anakinra). The review article also presents findings of various imaging methods (conventional radiography, computed tomography, traditional bone scintigraphy) and photographs of patients with Schnitzler syndrome before and after anakinra therapy.

DESIGN

The aim of the review is to draw attention to the existence of this rare autoinflammatory and potentially premalignant condition, present a simple diagnostic algorithm and provide an overview of therapeutic options for the patients.

CONCLUSIONS

Malign potential of Schnitzler syndrome, possible development into systemic amyloidosis and the fact that patients are frequently referred to oncology clinics for differential diagnostics of monoclonal gammopathy, are the main reasons why clinical oncologists should be aware of Schnitzler syndrome.