[Xanthogranulomatous pyelonephritis presenting a subcutaneous mass in the lower abdomen: a case report].

A 72-year-old female presented with the complaint of left lower abdominal swelling in May, 2005. Laboratory analysis revealed elevated white blood cell counts and C-reactive protein. Abdominal computed tomography showed left ureteral calculi, left hydronephrosis and a mass extending through the perinephric space, psoas major muscle into the left flank and lower abdomen. Echo-guided needle mass biopsy was performed. Histopathological findings revealed xanthogranulomatous changes. Under the diagnosis of diffuse xanthogranulomatous pyelonephritis extended into psoas muscle and subcutaneous tissue, antibiotic therapy was given for 5 months. After reduction of subcutaneous mass, left nephroureterectomy was performed. Histopathological findings revealed xanthogranulomatous pyelonephritis and ureteritis. Postoperative course was uneventful without any relapse of inflammation.