Rad Hub

Detail for incidental renal mass:
- size 
- attenuation (CT)/echogenicity (US)/signal (MRI) 
- homogeneity versus heterogeneity, 
- enhancement or Doppler flow, 
- internal complexity (incl. est. of Bosniak category for cystic) 
- any change from prior studies

Incidental renal mass on non-contrast CT

[Flowchart 1] If the mass contains fat attenuation (<–10 HU), proceed to Flowchart 6. If prior studies are available for comparison, indeterminate masses with no change in imaging features for at least 5 years can be considered clinically insignificant. CT = computed tomography; MR = magnetic resonance; TSTC = too small to characterize; WO&W = without and with.

Incidental renal mass on contrast CT

[Flowchart 2] If the mass contains fat attenuation (<–10 HU), proceed to Flowchart 6. If prior studies are available for comparison, indeterminate masses with no change in imaging features for at least 5 years can be considered clinically insignificant. CT = computed tomography; MR = magnetic resonance; TSTC = too small to characterize; WO&W = without and with.

Incidental renal mass on ultrasound

[Flowchart 3] See Table 1 for Bosniak classification system. If prior studies are available for comparison, indeterminate masses with no change in imaging features for at least 5 years can be considered clinically insignificant. AML = angiomyolipoma; CT = computed tomography; MR = magnetic resonance; MRI = MR imaging; RCC = renal cell carcinoma; U/S = ultrasound; WO&W = without and with.

Incidental cystic renal mass (CT/MR, no fat)

[Flowchart 4] See Table 1 for Bosniak classification system. CT = computed tomography; MR = magnetic resonance; U/S = ultrasound; WO&W = without and with.

Incidental solid mass / too small

[Flowchart 5] CT = computed tomography; MR = magnetic resonance; TSTC = too small to characterize; WO&W = without and with.

Incidental renal mass containing fat

[Flwochart 6] CT = computed tomography; MR = magnetic resonance; WO&W = without and with.

Source: Recommendations for the Management of the Incidental Renal Mass in Adults: Endorsement and Adaptation of the 2017 ACR Incidental Findings Committee White Paper by the Canadian Association of Radiologists Incidental Findings Working Group