ELSEV IER zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA EUROPEAN JOURNAL OF RADIOLOGV European Journal of Radiology 24 (1997) 77-79 Focal xanthogranulmatous pyelonephritis in a teenager: MR and CT findings Rafaela Soler* a, Francisco Pornboa, Ana Gayol”, Javier Rodriguezb ‘Department of Radiology, Hospital Juan Canalejo, Xubias de arriba, 84, La Con& 15006, Spain bDepartment of Urology, Hospital Juan Gamzlejo,La Cork. Spain Received 19 January 1996; revised 1 April 1996; accepted 3 April 1996 Keywords: Kidney, disease; Kidney, infection; Renal, masses; Radiography, infection 1. Introduction Xanthogranulomatous pyelonefritis (XGP) is an unusual form of chronic infection of the renal paren- chyma, pathologically characterized by the presence of large lipid-laden macrophages. Two forms of presenta- tion of XGP have been reported. Diffuse XGP that usually affects middle-aged women is the more frequent and it is characterized by an enlarged non-functioning kidney associated with calculus. The very unusual focal XGP is said to affect more commonly children and, due to its pseudotumoral appearance, can simulate primary renal neoplasm. We report a case of focal XGP in a functioning kidney with no associated calculus in a teenager. The CT and MR findings suggested the diagnosis of focal XGP that was confirmed by CT guided biopsy. Medical therapy was started with clinical improvement avoiding surgical management. 2. Case report A 14-year-old girl presented with a 2-week history of fever and weight loss of 6 pounds. Physical examination was otherwise unremarkable. Laboratory data showed mild leucocytosis and red blood cell sedimentation rate of 139 nun/h. Urinalysis demonstrated 50 WBC and 10 RBC. Urine culture demonstrated no growth. Computed tomography after intravenous administra- tion of contrast material demonstrated a heterogeneous ?? Corresponding author, Tel.: +34 81 178000 Ext-11044. soft tissue intrarenal mass, with low attenuation small areas (Fig. la). Infiltration of the neighboring psoas muscle was also identified. There was neither litiasis nor urinary tract obstruction. Magnetic resonance examination was performed on a 0.5Tesla superconductive unit with a body coil. Cor- onal and axial spin-echo Tl-weighted, axial T2-weighted and short tau inversion recovery (STIR) sequences were obtained. The mass had an intermediate signal on Tl-weighted images (Fig. lb) and was heterogeneous with central areas of hypointense signal on TZweighted (Fig. lc) and STIR sequence (Fig. Id). There was also hyperintensity in the psoas muscle. A CT guided biopsy was performed. The histology examination demonstrated inflammatory tissue with foamy histiocytes consistent with XGP. Antibiotherapy of broad spectrum was started and there was a very good clinical outcome. Follow-up imaging examination was performed with CT initially and later with ultra- sound; slow diminution of the renal mass was seen, achieving complete resolution 3 years later. 3. I%cusslon XGP is a chronic inflammatory disease which begins in the renal pelvis and extend to the parenchyma causing progressive destruction of the kidney. XGP is usually a diffuse process, with a female predominance, associated with an obstructing calculus and recurrent infection of the urinary tract [1,2]. Although urinary tract infection is always present with Proteus mirabilis and Escherichia coli being the agents most frequently found, urine cul- 0720-048X:97,‘$17.00 Copyright 8 1997 Elsevier Science Ireland Ltd. All rights reserved PII SO720-048X(96)01025-X