66 year old woman recalled history of recurrent episodes of back pain and fever some years ago. She now has impaired renal function.
This is a longitudinal slice of the kidney. The kidney is scarred. Cut surface shows yellowish orange nodules of xanthogranulomatous inflammation in the hilar region and renal parenchyma. On imaging, these may be mistaken for a neoplasm.
There is also blurring of the corticomedullary junction and dilation of the pevicalyceal system