“Schnitzler syndrome is an autoinflammatory disease characterized by chronic, nonpruritic urticaria in association with recurrent fever, bone pain, arthralgia or arthritis, and a monoclonal gammopathy, most often of the immunoglobulin M (IgM) subtype. Approximately 10-15% of patients eventually develop a lymphoproliferative disorder, such as lymphoplasmacytic lymphoma, Waldenström macroglobulinemia, or IgM myeloma.”.

MedScape (https://emedicine.medscape.com/article/1050761)