🫘 Renal Cystic Lesion Bosniak Classification (CT/MRI)
Look up the malignancy risk and management for a Bosniak 2019 renal cystic-lesion category (I–IV). Instant, browser-side.
Clinical takeaway
The 2019 version unified the enhancement definition (CT ≥ 20 HU or MR ≥ 15%).
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When to use
Translate a Bosniak category into a no-follow-up, imaging-follow-up or surgical pathway.
How it works
I/II benign (~0%) no follow-up; IIF probably benign (~5%) imaging follow-up; III indeterminate (~50%) surgery or active surveillance; IV malignant (~90%) surgery. Enhancement = CT ≥ 20 HU or MR ≥ 15%.
Key points
- The 2019 version unified the enhancement definition (CT ≥ 20 HU or MR ≥ 15%).
- Morphologic upgrade on follow-up strongly predicts malignancy and warrants reclassification.
- Biopsy of cystic lesions is generally not recommended (except category IV).
- Category III management balances surgery vs active surveillance by age and comorbidity.
References
Decision support for licensed clinicians only; not a substitute for clinical judgement, diagnosis or local protocols.
Worked calculation
The values below come from this tool's own example placeholders and are computed server-side with the formula shown on this page, so the arithmetic can be checked quickly. It demonstrates how to substitute values only — it is not clinical advice and not a real case.
| Bosniak category (2019 version) | I — Simple cyst |
|---|
→ManagementNo follow-up
- Category：Bosniak I: Benign (essentially 0%)
- Management：Simple cyst (thin ≤ 2 mm smooth wall, homogeneous simple fluid, no septa/calcification; wall may enhance): no follow-up
- Enhancement criteria：2019 unified enhancement definition: CT attenuation increase ≥ 20 HU vs unenhanced, or MR signal increase ≥ 15%; thin = ≤ 2 mm, minimally thick = 3 mm, many = ≥ 4 septa
| Bosniak category (2019 version) | IV — Clearly malignant |
|---|
→ManagementSurgery
- Category：Bosniak IV: Clearly malignant (~90%)
- Management：Contains enhancing soft-tissue/nodular components: surgery (partial/radical nephrectomy), managed as renal cell carcinoma
- Enhancement criteria：2019 unified enhancement definition: CT attenuation increase ≥ 20 HU vs unenhanced, or MR signal increase ≥ 15%; thin = ≤ 2 mm, minimally thick = 3 mm, many = ≥ 4 septa
Frequently asked questions
- What is Renal Cystic Lesion Bosniak Classification (CT/MRI)?
- Look up the malignancy risk and management for a Bosniak 2019 renal cystic-lesion category (I–IV). Instant, browser-side.
- How is Renal Cystic Lesion Bosniak Classification (CT/MRI) calculated? What is the core formula?
- I/II benign (~0%) no follow-up; IIF probably benign (~5%) imaging follow-up; III indeterminate (~50%) surgery or active surveillance; IV malignant (~90%) surgery. Enhancement = CT ≥ 20 HU or MR ≥ 15%.
- When is Renal Cystic Lesion Bosniak Classification (CT/MRI) used?
- Translate a Bosniak category into a no-follow-up, imaging-follow-up or surgical pathway.
- What are the key clinical points for Renal Cystic Lesion Bosniak Classification (CT/MRI)?
- The 2019 version unified the enhancement definition (CT ≥ 20 HU or MR ≥ 15%). Morphologic upgrade on follow-up strongly predicts malignancy and warrants reclassification. Biopsy of cystic lesions is generally not recommended (except category IV). Category III management balances surgery vs active surveillance by age and comorbidity.
- What are the limits and cautions when using Renal Cystic Lesion Bosniak Classification (CT/MRI)?
- For licensed clinicians and clinical researchers. Interpret results with history, investigations and local protocols; not a diagnosis or prescription, and not a substitute for multidisciplinary decision-making or local guidelines.
- How is Renal Cystic Lesion Bosniak Classification (CT/MRI) calculated in practice? Can you show a worked example?
- Inputs: Bosniak category (2019 version) I — Simple cyst → Result: Management No follow-up（Category: Bosniak I: Benign (essentially 0%), Management: Simple cyst (thin ≤ 2 mm smooth wall, homogeneous simple fluid, no septa/calcification; wall may enhance): no follow-up, Enhancement criteria: 2019 unified enhancement definition: CT attenuation increase ≥ 20 HU vs unenhanced, or MR signal increase ≥ 15%; thin = ≤ 2 mm, minimally thick = 3 mm, many = ≥ 4 septa） Inputs: Bosniak category (2019 version) IV — Clearly malignant → Result: Management Surgery（Category: Bosniak IV: Clearly malignant (~90%), Management: Contains enhancing soft-tissue/nodular components: surgery (partial/radical nephrectomy), managed as renal cell carcinoma, Enhancement criteria: 2019 unified enhancement definition: CT attenuation increase ≥ 20 HU vs unenhanced, or MR signal increase ≥ 15%; thin = ≤ 2 mm, minimally thick = 3 mm, many = ≥ 4 septa）