· Low attenuation fatty mass, replacing the right renal parenchyma, extends beyond the kidney into the perinephric space ( green arrow), with loss of normal renal
outline, along with deformed appearance of the remaining part of the kidney which harbouring multiple stones ( yellow arrow ) and shows mild hydronephrosis ( white arrow )
· Normal appearance of left kidney ( pink arrow ).
Xanthogranulomatous pyelonephritis (XGP)
· XGP is a rare chronic suppurative form of renal infection due to chronic renal
obstruction ( calculus or stricture) resulting in a non-functioning kidney
characterized by parenchymal destruction and replacement of the parenchyma with
lipid laden macrophages
· The kidney is eventually replaced by a mass of reactive tissue, surrounding the usually present calculus with associated hydronephrosis of a greater or lesser degree. Foamy (lipid laden) macrophages predominate .
· Inflammatory process eventually extends into perinephric tissues and even adjacent organs.
· Two forms are recognized, diffuse form ( 90% of cases ) , and focal form ( 10% of cases )
· F:M = 4:1. the female predilection is presumably relating to an increased incidence of urinary tract infections .