Table 3: Bosniak Renal Cyst Classification. Adopted from Eknoyan G. A Clinical View of Simple and Complex Renal Cysts. J Am Soc Nephrol 20: 1874-1876, 2009

Category	Cyst Wall	Septae	Calcification	Enhancement
I	Hairline thin	No	No	No
II	Minimal regular thickening	Few, hairline thin	Smooth, hairline thin	No
IIF	Minimal regular thickening	Multiple, minimal smooth thickening	Thick, nodular	No
III	Irregular thickening	Measurably thick, irregular	Thick, nodular, irregular	Yes
IV	Gross irregular thickening	Irregular gross thickening	Thick, nodular, irregular	Yes, tissue and cyst