| Classification | Description | Notes |
|
1 |
Simple cyst, hairline thin wall, no septa, calcifications, solid components or enhancement | Benign |
|
2 |
Few hairline thin septa, minimal calcification.
High-density cysts: <3cm, uniform, well marginated, non-enhancing |
No further evaluation needed |
|
2F |
Multiple hairline septa, minimal smooth wall thickening, non-enhancing.
Intrarenal non-enhancing high-density cysts >3cm |
Needs follow-up |
|
3 |
Cystic mass with thickened, irregular or smooth walls with measurable enhancement. | Indeterminate. Surgical lesion. |
|
4 |
Cystic mass with enhancing soft-tissue component | Clearly malignant. Surgical lesion |
Reference:
Israel, G. M. and M. A. Bosniak (2005). “An update of the Bosniak renal cyst classification system.” Urology 66(3): 484-488.