Xanthogranulomatous pyelonephritis: an uncommon pediatric renal mass.

Xanthogranulomatous pyelonephritis (XGP) is a chronic suppurative infectious process that only rarely affects pediatric patients, and most commonly occurs in the setting of a large obstructing calculus. Histologically, XGP is characterized by the presence of chronic inflammation and lipid-laden macrophages. This case report illustrates the radiological, surgical, and pathologic findings in a young patient who presented to our institution for treatment of this uncommon condition. Although rare, xanthogranulomatous pyelonephritis is a clinically important entity that can affect pediatric patients. This condition should be considered in the differential diagnosis for an atypical-appearing renal mass.