IgG4-Related Systemic Disease Can Be Easily Mistaken as a Uroepithelial Tumor

Abstract

Immunoglobulin G4-related disease (IgG4-RD) is a newly recognized systemic syndromecharacterized by elevated serum IgG4 concentrations and tumefaction or tissueinfiltration by IgG4-positive plasma cells. We experienced a case of IgG4-RD involvingmultiple organs in a 64-year-old female who was referred for a suspected uroepithelialtumor. A mass biopsy confirmed dense lymphoplasmacytic infiltration with an increasednumber of IgG4-positive plasma cells. We discuss this case and review the literatureto bring IgG4-RD to the attention to clinicians because it responds dramaticallywell to steroid therapy and should be kept in mind as a differential diagnosis to avoidunnecessary surgery.