RADIOLOGY: KIDNEY: Case# 33681: XANTHOGRANULOMATOUS PYELONEPHRITIS VS. CHRONIC HYDRONEPHROSIS/PYONEPHROSIS; MULTIPLE RIB FRACTURES. 90 year old female in MVA. 1. No intraabdominal parenchymal injury. No free air or hematomas. 2. Right renal staghorn calculus. Cortical thinning is present in the right kidney with hydronephrosis; consider xanthogranulomatous pyelonephritis vs. chronic hydronephrosis/pyonephrosis. 3. No contrast extravasation from the bladder. 4. Multiple rib fractures.