Schnitzler syndrome.

Schnitzler syndrome is characterized by monoclonal IgM gammopathy, urticaria, recurrent fever, evidence of inflammation, bone pain, and arthralgia, occasionally in combination with lymphadenopathy and/or hepatosplenomegaly. Only about 80 cases have been reported to date. Development of a hematological malignancy is the main complication. Recent reports of remissions induced by IL-1 receptor antagonist therapy shed new light on the pathophysiology of the disease.