Schnitzler's syndrome as cause of recurrent fever of unknown origin

History and clinical findings: For 4 years a 56-year-old woman had been suffering from chronic urticaria, In the past two years she had developed recurrent fever, each 1-3 days in duration. In the last 6 to 8 months she also had severe aching in the legs. There were no significant findings on physical examination other than non-itching urticarial rash over trunk and limbs. Investigations: Blood sedimentation rate was increased (maximum 88/110 mm), as were WBC count (16,200/mu l, 83% neutrophils) and the activity of alkaline leucocyte phosphatase (225 U/l). Monoclonal IgM gammopathy type kappa and circulating IgM immune complex (15.4 mg/dl) were demonstrated in serum. Skin biopsy of a new urticarial lesion revealed vasculitis. Iliac crest biopsy was unremarkable and showed no lymphoid cell infiltration. Bone scintigraphy revealed bilaterally increased storage in femor and tibia. Magnetic resonance imaging demonstrated marrow infiltration without space-occupying features in the affected femur and tibia. Treatment and course: Conjunction of fever, generalised urticaria, joint/bone pain and monoclonal gammopathy of kappa type having established the diagnosis of Schnitzler's syndrome, treatment with ibuprofen was started (initially 1,200 mg daily by mouth, followed by reduction to 600 mg daily). All symptoms rapidly improved and the bone changes regressed, but not the monoclonal gammopathy. But when the ibuprofen dosage had been decreased to 600 mg daily, the urticaria recurred, though in milder form. Conclusion: This case demonstrates the efficacy of ibuprofen in the treatment of the Schnitzler's syndrome. Furthermore reversibility of scintigraphic bone lesions could be demonstrated under ibuprofen treatment.