Schnitzler's syndrome presenting as fever of unknown origin (FUO). The role of cytokines in its systemic features.

A patient with Schnitzler's syndrome is described presenting with fever of unknown origin. Although he had all characteristic features of the syndrome (urticarial vasculitis, hyperostosis, lymphadenopathy, fever and serum IgM monoclonal component), it was recognized very late in the diagnostic process. Cytokines were measured to get more insight into the role of cytokines in this syndrome, but only interleukin-6 was elevated. It is important for internists and rheumatologist to recognize this entity in order to prevent unnecessary diagnostic procedures.