CT of xanthogranulomatous pyelonephritis: radiologic-pathologic correlation

Area of Science:

• Radiology
• Pathology
• Urology

Background:

• Xanthogranulomatous pyelonephritis (XGP) is a rare, chronic destructive inflammatory condition of the kidney.
• Accurate diagnosis and staging are essential for appropriate management.

Observation:

• A study correlated clinical, radiological (CT scans), and pathological findings in 18 patients with XGP.
• Common symptoms included pain, urinary issues, palpable mass, leukocytosis, and fever, often with a short duration.
• CT scans revealed diffuse or focal XGP, with characteristic low-density areas and enhancing rims, and frequently showed unsuspected extension into surrounding spaces.

Findings:

• The kidney was often enlarged, with contracted renal pelvis and pelvic calculi in most cases.
• Extensive involvement of the pararenal spaces and psoas muscle was noted, sometimes with minimal perirenal disease.
• Preoperative diagnosis of XGP was suspected in only 44% of cases, highlighting diagnostic challenges.

Implications:

• CT imaging is vital for diagnosing XGP and assessing the full extent of extrarenal disease, which is often underestimated.
• Improved preoperative planning through CT can lead to better surgical outcomes for patients with XGP.
• The findings underscore the importance of considering XGP in the differential diagnosis of complex renal masses and infections.