Diagnostic Difficulties in Diffuse Xanthogranulomatous Pyelonephritis: A Case Report and Review of the Literature

Xanthogranulomatous pyelonephritis is a rare, severe, and chronic infection of the kidney characterized by the replacement of renal parenchyma by the xanthoma cells which is difficult to diagnose radiologically. We report a 40-year-old male who had vague abdominal mass and fever for more than 2 months. Weight loss and fatigue were the associated symptoms. Ultrasonography revealed a grossly enlarged right kidney with replacement of renal parenchyma by multiple hypoechoic areas with perinephric thickening and a large staghorn calculus. An abdominal computed tomogram demonstrated an irregular, enlarged right kidney with multiple low-density round areas and calculi. Diminished excretion of contrast media and a severe perinephric inflammatory reaction were present. A presurgical diagnosis of xanthogranulomatous pyelonephritis was made. First, drainage of the extrarenal abscess under proper antibiotic coverage was done and later, a two stage nephrectomy was done considering the debilitating condition of the patient.