Table 2.

Differential diagnoses table for Xanthogranulomatous pyelonephritis (XGP).

	US	CT	MRI
XGP	Renal enlargement with pelvicalyceal dilatation, parenchymal destruction and multiple anechoic areas with hyperechogenic septa.	Multiloculated appearance (low density rounded areas throughout the enlarged left kidney): bear’s paw sign.	T1-weighted: Cavitary borders: Hyperintense Cavitary fluid: Hypointense Perirenal strands: Hypointense T2-weighted: Cavitary borders: Isointense Cavitary fluid: Hyperintense Perirenal strands: Hypointense Fluid level: Present Gd-DTPA: Cavitary borders: Enhancement. Cavitary fluid: No enhancement Perirenal strands: Enhancement
Clear cell RCC	Can be hypo-iso-hyperechoic and heterogeneous [10].	Hypodense and hyperdense parenchymal mass with hemorrhage and necrosis [10].	Hypo to isointense on T1. Iso to hyperintense on T2. Drop on in signal due to microscopic fat [10].
Sarcomatoid RCC	Large solid to cystic mass [10,11].	Solid hypodense mass [10,11].	Necrosis is evident as hypointense signal on T1 with corresponding T2 hyperintensity [10,11].
Tuberculosis	Necrotic heterogeneous mass	Mass with calcifications and cortical scarring	Hypoperfused areas on contrast-enhanced, fat-suppressed T1 Central hyperintense areas on T2 [12].
Angiomyolipoma	Intense echogenicity Well-circumscribed [13].	Cortical heterogeneous lesion with fatty (low) attenuation Variable enhancement pattern [13].	High intensity on non-enhanced T1 (fat) Isointense to perinephric fat on T2 [13].
Renal Abscess	Anechoic/hypoechoic complex cystic mass [14].	Low-attenuation mass with peripheral enhancement and possible gas collections [14].	Peripherally enhancing mass and gas collections [14].