Xanthogranulomatous Pyelonephritis: A Narrative Review with Current Perspectives on Diagnostic Imaging and Management, Including Interventional Radiology Techniques.

Xanthogranulomatous Pyelonephritis (XGP) is a rare, chronic granulomatous inflammatory condition thought to arise secondary to a combination of obstruction, recurrent bacterial infection and an incomplete immune response resulting in focal or diffuse renal destruction. This destruction may be profound with the potential to infiltrate surrounding tissues and viscera. The imaging features of XGP can be ambiguous, mimicking malignancy, tuberculosis (TB) and malakoplakia earning the title of "the great imitator". Computed tomography (CT) is the mainstay of XGP diagnosis and staging, accurately quantifying the stone burden and staging the renal destruction, including the extent of extra-renal spread. Although some cases in children have been successfully treated with antibiotics alone, nephrectomy remains the most common treatment for XGP in adults. The specific management strategy needs to be tailored to individual patients given the potential constellation of renal and extrarenal abnormalities. Although XGP has classically required open nephrectomy, laparoscopic nephrectomy has an increasing role to play arising from the advancement in laparoscopic skills, technique and instruments. Nephron-sparing partial nephrectomy may be considered in the focal form. Interventional radiology techniques most often play a supportive role, eg, in the initial drainage of associated abscesses, but have rarely achieved renal salvage. This narrative review seeks to synthesise the existing literature and summarise the radiological approach and interventional radiology management situated in a clinical context.