| Bosniak Classification |
CT Features |
Processing |
| Class I |
①Simple cyst with thin and slender wall, no separation, calcification or solid components; ②Uniform watery density foci (CT value 0-20 HU); ③Defined border with smooth and sharp edges; ④No enhancement on enhancement scan |
Benign |
| Class II |
①Benign cysts may be associated with slender partitions; ②Tiny calcifications may be present in the cyst wall or partitions; ③<3 cm of uniformly dense cyst; ④Sharp border without enhancement |
Benign |
| Class IIF |
① Slightly increased fibrous partitions with slight uniform thickening and enhancement of the cyst wall or partitions; ② Slightly thickened or nodular calcification within the cyst without enhancement; ③ Soft tissue component without enhancement; ④ Dense cysts ≥3 cm in diameter located entirely within the renal parenchyma. Usually well-defined borders |
Follow-up to 5 years is partially malignant |
| Class III |
①Difficult to characterize cyst with irregular or uniform thickening of the cyst wall or compartment; ②Enhancement seen on enhanced scan |
Surgery or active follow-up, more than 50% malignant |
| Class IV |
With typical signs of malignancy: soft tissue component with enhancement |
Surgery
Mostly malignant |