Xanthogranulomatous Pyelonephritis in a Horseshoe Kidney: Effective Conservative Therapy in an Immunocompromised Patient.

Xanthogranulomatous pyelonephritis (XGPN) is a rare, chronic granulomatous inflammation that leads to diffuse destruction of the renal parenchyma. This destructive process may be so profound as to infiltrate surrounding tissues and viscera. Although nephrectomy remains the most common option for managing XGPN in adults, we report a case of XGPN in a horseshoe kidney of a 27-year-old woman on active immunosuppressive therapy for inflammatory bowel disease, namely ulcerative colitis. This case was successfully treated conservatively with antimicrobials, with complete resolution of the renal mass and improvement in the general condition and inflammatory markers.