Xanthogranulomatous pyelonephritis mimicking perirenal abscess. Case report

Abstract

Introduction: Perirenal abscess is an uncommon but potentially severe condition often related to urinary tract infection, obstruction, and renal calculi. Xanthogranulomatous pyelonephritis (XGP) is a rare chronic inflammatory process that results in progressive renal destruction and frequently presents diagnostic difficulty. Case report: A 35-year-old woman presented with a 7-day history of a painful right lumbar mass. Plain abdominal radiography revealed right renal calcified nephrolithiasis. Surgical drainage yielded 400 mL of greenish purulent fluid, with cultures positive for Proteus mirabilis. Subsequent CT imaging demonstrated a staghorn calculus, right hydronephrosis, and ureterolithiasis. A second procedure revealed a markedly enlarged and destroyed kidney containing purulent material and multiple calculi. Histopathological examination confirmed xanthogranulomatous pyelonephritis. The patient recovered uneventfully after surgery. Conclusions: XGP should be suspected in patients with perirenal abscesses associated with renal obstruction or nephrolithiasis. Early imaging, timely drainage, and appropriate surgical management are essential to achieve an accurate diagnosis and ensure favorable clinical outcomes.