Chronic urticaria, arthralgia, raised erythrocyte sedimentation rate and IgG paraproteinaemia: a variant of Schnitzler's syndrome?

Schnitzler's syndrome is a distinct disease entity characterized by the association of chronic urticaria, intermittent fever, arthralgia, elevated erythrocyte sedimentation rate and IgM macroglobulinaemia. We report a patient with the same symptoms, but a monoclonal IgG instead of IgM gammopathy. Histological examination of the urticarial lesions showed signs of mild leucocytoclastic vasculitis. Except for the different class of the monoclonal immunoglobulin, the clinical symptoms, laboratory findings and histology in this patient were identical with those in classical Schnitzler's syndrome. IgG and IgM paraproteins may be equivalent with regard to the putative pathophysiology of the disease process in Schnitzler's syndrome. We therefore suggest that the spectrum of Schnitzler's syndrome is expanded to include patients with chronic urticaria and monoclonal IgG gammopathy, as a closely related variant.