Table 1.

Differential diagnoses of angiomyolipoma

MASSES	US	CT	MRI
			T1W	T2W
Angiomyolipoma	Hyperechoic; can be multiple in tuberous sclerosis complex;	Pure fat/intermixed soft tissue with moderate enhancement; no calcification	Iso to Hyperintense with suppression on fat saturated images.	Hyperintense. in out phase imaging for microscopic fat shows signal drop.
Lipoma/liposarcoma	Hyperechoic; Lipomas are well encapsulated with pure fat content; intermixed soft tissue seen in liposarcoma;	Lipomas are well encapsulated with pure fat content; intermixed soft tissue with enhancement seen in liposarcoma; +/− calcification;	hyperintense with suppression on fat saturated sequences; hypointense if myxoid/soft tissue component dominates; +/− enhancement	Hyperintense
Renal cell carcinoma -tumor containing fat -lipid producing necrosis -engulfed perirenal or sinus fat	Hypo/iso/hyper echoic on US;	Hypodense soft tissue attenuating; presence of calcification; contrast enhancement less than renal parenchyma;	Hypointense; enhancement less than renal parenchyma	Hyperintense
Oncocytomas	Hypo; variable	+/− calcification; show typical spoke wheel pattern of contrast enhancement	Hypo/iso intense	Iso to hyperintense with hypointense central scar. “Spoke wheel” pattern of contrast enhancement.
Xanthogranulomatou s pyelonephritis (chronic granulomatous inflammation)	Large renal calculus in >90% cases with hydronephrosis and peripheral hyperechogenicity	Large renal calculus with hydronephrosis and peripheral fat attenuation. If microscopic fat then low attenuating. Usually non functioning kidney.	‘Great mimicker of malignancy’ peripheral fat hyperintense with suppression on fat saturated sequence. Usually no contrast enhancement	Hyperintense. Calculus is signal void in all sequences