Schnitzler's Syndrome with IgG κ Gammopathy

A Seventy-year-old man with a variant type of Schnitzler's syndrome is reported. Physical examination showed pruritic urticarial lesions on the extremities, arthralgia of knee joints, and intermittent fever. Laboratory investigations revealed a high level of IgG, an increased erythrocyte sedimentation rate, urinary Bence-Jones protein, and an M-bow in serum protein electrophoresis, which was shown to be a monoclonal IgG K type. Histological examination showed perivascular neutrophil and lymphocytic infiltration into the upper dermis and diffuse neutrophilic infiltration in the middle dermis. One of the clinical features of typical Schnitzler's syndrome is IgM macroglobulinemia, and this is a very rare case of this syndrome with IgG gammopathy.