Management of kidney cysts according to Bosniak category

US: ultrasound; CT: computed tomography; MRI: magnetic resonance imaging; IV: intravenous.

* Refer to UpToDate content on simple and complex cysts for radiographic criteria for simple cysts (US, CT, and MRI).

¶ MRI may not be necessary for Bosniak IIF lesions if prior imaging studies are available for comparison. Refer to UpToDate content on simple and complex cysts for additional details.

Δ For patients with a complex kidney cyst who cannot receive iodinated contrast or gadolinium, options vary and can range from surveillance imaging with multiple modalities (eg, noncontrast MRI and US) to surgical resection in some patients. Refer to UpToDate content on simple and complex cysts for additional details.

◊ Radiographic evolution of a IIF cyst on follow-up US requires further characterization by contrast-enhanced CT or MRI.

§ Bosniak III and IV complex cysts have an increased risk of malignancy. Management options include surgical resection, thermal ablation, and, in selected patients, active surveillance. Refer to UpToDate content on simple and complex cysts for additional details.