IgG4-related Periarteritis Successfully Diagnosed by an Alternative Prostate Biopsy.

A 56-year-old man was referred to our facility after developing edema in his right leg. Enhanced computed tomography (CT) revealed a periarterial soft tissue mass surrounding the right iliac artery compressing the iliac vein. His elevated serum IgG4 level indicated IgG4-related disease (IgG4-RD). Both a percutaneous and surgical biopsy of this periarterial lesion proved challenging and were not pursued. A prostate biopsy, however, finally provided a histological diagnosis of IgG4-RD. Oral steroid therapy successfully resolved his leg edema and periarterial lesion. This case illustrates the usefulness of an alternative prostate biopsy for the histological diagnosis of IgG4-RD when approaching the primary affected lesion is difficult.