A 50-year-old woman with recurrent urinary infections and persistent flank pain has a diffusely enlarged, non-functioning right kidney. Contrast CT shows multiple hypodense cavities replacing the parenchyma arranged around a central calcification, described as the bear paw sign. What is the standard treatment?
- A Long-course antibiotics with radiological follow-up
- B Nephrectomy ✓
- C Percutaneous drainage of the cavities
- D Extracorporeal shock wave lithotripsy
Explanation
Xanthogranulomatous pyelonephritis is a chronic destructive granulomatous infection of the kidney, almost always associated with obstructing calculi and Proteus or E coli infection. The bear paw sign describes lipid-laden macrophage-filled cavities surrounding the pelvis. Because the kidney is functionally destroyed and the disease can extend to adjacent structures, nephrectomy is the standard treatment; partial nephrectomy is possible in focal disease. Antibiotics suppress symptoms but cannot eradicate the disease, and lithotripsy or simple drainage are ineffective for a non-functioning kidney.
Reference: Smith and Tanagho's General Urology, 19th ed.
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Written and medically reviewed by the StethoPrep medical team.