A man in his fifties with recurrent urticaria, fever and joint pain.

Background: Schnitzler's syndrome is a rare, acquired and probably underdiagnosed disorder. It is a type of autoinflammatory condition with late onset.

Case Presentation: A man in his fifties had had recurrent urticaria, fever and chronic joint pain during the previous year. After an extensive investigation, no evidence of infection, autoimmune disease or malignancy was found. Blood samples showed moderately elevated SR and CRP, mild thrombocytosis and presence of monoclonal IgM in low concentration (MGUS). The combination of sterile inflammation, joint/muscle pain, urticaria and M-component was consistent with Schnitzler's syndrome. He was placed on a treatment trial with anakinra (interleukin [IL]-1 receptor antagonist) 100 mg x 1 daily, given as a subcutaneous injection. His condition was excellent until one week after the first injection. The initial treatment indicated a good clinical effect of IL-1 blockade, but due to the very unpleasant localised side effects (extensive dermatitis), treatment with anakinra was withdrawn, and canakinumab (monoclonal antibody against IL-1β) was chosen instead. He responded very well to this treatment and experienced no adverse effects. One year after starting treatment, the patient still has an excellent treatment response.

Interpretation: Anakinra is the treatment of first choice for this condition, but this case history illustrates that canakinumab can be tried if anakinra is not tolerated by the patient.