Table 2.

Frequency of malignancy in cystic lesions, stratified by Bosniak classification; studies with more than 30 patients.

Study	Bosniak category
	I	II	IIF	III	IV
Siegel et al.(18)	0/22	1/8	—	5/11	26/29
Koga et al.(11)	0/11	1/2	—	10/10	12/12
Israel et al.(19)	—	—	0/39	2/3	—
O'Malley et al.(20)	—	—	0/81	27/33	—
Song et al.(15)	0/3	3/26	0/3	21/38	32/37
Smith et al.(17)	—	—	4/16	58/107	—