Table 2.

Fat-containing renal masses on CT: imaging clues

	Classic AML	RCC with macroscopic fat	Oncocytoma with perinephric fat extension
Tumour size	Variable	Variable but often large in RCCs with perinephric fat engulfment	Variable
Calcification	− (Rare)	+	±
Intratumoral aneurysm	+	−	−
Cystic/necrotic change	− (Rare)	+	±
Hypervascular mass	+	+	+
Central scar	−	−	+
Vascular invasion	− (Rare)	+	− (Rare)
Distant metastasis	−	+	−

Note: AML, angiomyolipoma; RCC, renal cell carcinoma.