Skip to main content

Bosniak Classification Version 2019: A CT-Based Update for Radiologists

Current Radiology Reports volume 10, pages 83–92 (2022)Cite this article

Abstract

Purpose of Review

To review the recent revision of the Bosniak classification: version 2019 (v2019), with emphasis on CT, comparing v2019 to the original Bosniak classification (last updated in 2005) and discuss why this revision was needed and is clinically useful. To present an approach to apply v2019 in practice, reviewing available validation studies evaluating inter- and intra-observer agreement, diagnostic test accuracy, and intermodality comparisons between CT (including dual-energy CT), MRI, and Ultrasound.

Recent Findings

After the 2019 proposal revising the Bosniak classification of Cystic Renal masses, data have emerged, which support use of the revised system. These include higher prevalence of malignancy in class III and IV cystic masses and slightly improved interobserver agreement with less discrepancy between class assignment comparing CT and MRI. However, studies have shown limitations of v2019 which include high dispersion of agreement regarding wall or septa feature (e.g., irregularity versus nodule), a higher proportion of malignancy in class IIF and persistent upgrading of class comparing MRI to CT.

Summary

Overall, the recent Bosniak v2019 revision has advanced the field of cystic renal mass imaging by achieving a consensus for terminologies and definitions, slightly improving interobserver agreement (with the opportunity for future iterations to improve upon these preliminary results) and increasing specificity of diagnosis of malignancy in higher Bosniak v2019 classes without impacting sensitivity. Future work is needed to simplify and potentially improve performance of the system and accommodate emerging techniques such as dual-energy CT and artificial intelligence.

This is a preview of subscription content, access via your institution.

Access options

Buy single article

Instant access to the full article PDF.

USD 39.95

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7
Fig. 8

References

Papers of particular interest, published recently have been highlighted as: • Of importance •• Of major importance

  1. Bosniak MA. The current radiological approach to renal cysts. Radiology. 1986;158(1):1–10.

    CAS  Article  Google Scholar 

  2. Bosniak MA. Problems in the radiologic diagnosis of renal parenchymal tumors. Urol Clin N Am. 1993;20(2):217–30.

    CAS  Article  Google Scholar 

  3. Ljungberg B, Albiges L, Abu-Ghanem Y, Bensalah K, Dabestani S, Fernandez-Pello S, et al. European Association of Urology Guidelines on Renal Cell Carcinoma: The 2019 Update. Eur Urol. 2019;75(5):799–810.

    Article  Google Scholar 

  4. Israel GM, Bosniak MA. Calcification in cystic renal masses: is it important in diagnosis? Radiology. 2003;226(1):47–52.

    Article  Google Scholar 

  5. Israel GM, Bosniak MA. An update of the Bosniak renal cyst classification system. Urology. 2005;66(3):484–8.

    Article  Google Scholar 

  6. •• Silverman SG, Pedrosa I, Ellis JH, Hindman NM, Schieda N, Smith AD, et al. Bosniak Classification of Cystic Renal Masses, Version 2019: an update proposal and needs assessment. Radiology. 2019;292(2):475–88. This reference is important because it related to the main topic.

  7. Schieda N, Krishna S, Pedrosa I, Kaffenberger SD, Davenport MS, Silverman SG. Active surveillance of renal masses: the role of radiology. Radiology. 2022;302(1):11–24.

    Article  Google Scholar 

  8. Bai X, Sun SM, Xu W, Kang HH, Li L, Jin YQ, et al. MRI-based Bosniak Classification of Cystic Renal Masses, Version 2019: interobserver agreement, impact of readers’ experience, and diagnostic performance. Radiology. 2020;297(3):597–605.

    Article  Google Scholar 

  9. • Edney E, Davenport MS, Curci N, Schieda N, Krishna S, Hindman N, et al. Bosniak classification of cystic renal masses, version 2019: interpretation pitfalls and recommendations to avoid misclassification. Abdom Radiol (NY). 2021;46(6):2699–711. This reference is important because it related to the main topic.

  10. • Schieda N, Davenport MS, Krishna S, Edney EA, Pedrosa I, Hindman N, et al. Bosniak classification of cystic renal masses, version 2019: a pictorial guide to clinical use. Radiographics. 2021;41(3):814–28. This reference is important because it related to the main topic.

  11. carcinoma SoARD-fpoRC.https://abdominalradiology.org/wp-content/uploads/2020/11/RCC.CTprotocolsfinal-7-15-17.pdf.

  12. McGrath TA, Shoeib A, Davenport MS, Silverman SG, McInnes MDF, Schieda N. Evaluation of class II cystic renal masses proposed in Bosniak classification version 2019: a systematic review of supporting evidence. Abdom Radiol (NY). 2021;46(10):4888–97.

    Article  Google Scholar 

  13. Dilauro M, Quon M, McInnes MD, Vakili M, Chung A, Flood TA, et al. Comparison of contrast-enhanced multiphase renal protocol CT versus MRI for diagnosis of papillary renal cell carcinoma. AJR Am J Roentgenol. 2016;206(2):319–25.

    Article  Google Scholar 

  14. Corwin MT, Loehfelm TW, McGahan JP, Liang C, Khati NJ, Haji-Momenian S. Prevalence of low-attenuation homogeneous papillary renal cell carcinoma mimicking renal cysts on CT. AJR Am J Roentgenol. 2018;211(6):1259–63.

    Article  Google Scholar 

  15. Herts BR, Silverman SG, Hindman NM, Uzzo RG, Hartman RP, Israel GM, et al. Management of the incidental renal mass on CT: a white paper of the ACR Incidental Findings Committee. J Am Coll Radiol. 2018;15(2):264–73.

    Article  Google Scholar 

  16. • Smith AD, Abou EA. Approach to renal cystic masses and the role of radiology. Radiol Clin N Am. 2020;58(5):897–907. This reference is important because it related to the main topic.

  17. Chan J, Yan JH, Munir J, Osman H, Alrasheed S, McGrath T, et al. Comparison of Bosniak Classification of cystic renal masses version 2019 assessed by CT and MRI. Abdom Radiol (NY). 2021;46(11):5268–76.

    Article  Google Scholar 

  18. Krishna S, Schieda N, Pedrosa I, Hindman N, Baroni RH, Silverman SG, et al. Update on MRI of cystic renal masses including Bosniak Version 2019. J Magn Reson Imaging. 2021;54(2):341–56.

    Article  Google Scholar 

  19. Yenice MG, Sam E, Arikan Y, Turkay R, Atar FA, Sahin S, et al. Comparison of computed tomography and magnetic resonance imaging in the assessment of complex renal cysts by using the Bosniak classification. Actas Urol Esp (Engl Ed). 2020;44(4):207–14.

    CAS  Article  Google Scholar 

  20. Yan JH, Chan J, Osman H, Munir J, Alrasheed S, Flood TA, et al. Bosniak Classification version 2019: validation and comparison to original classification in pathologically confirmed cystic masses. Eur Radiol. 2021;31(12):9579–87.

    Article  Google Scholar 

  21. Tse JR, Shen J, Shen L, Yoon L, Kamaya A. Bosniak Classification of cystic renal masses version 2019: Comparison of categorization using CT and MRI. AJR Am J Roentgenol. 2021;216(2):412–20.

    Article  Google Scholar 

  22. Park MY, Park KJ, Kim MH, Kim JK. Bosniak classification of cystic renal masses version 2019: Comparison With version 2005 for class distribution, diagnostic performance, and interreader agreement using CT and MRI. AJR Am J Roentgenol. 2021;217(6):1367–76.

    Article  Google Scholar 

  23. Schoots IG, Zaccai K, Hunink MG, Verhagen P. Bosniak classification for complex renal cysts reevaluated: a systematic review. J Urol. 2017;198(1):12–21.

    Article  Google Scholar 

  24. Graumann O, Osther SS, Karstoft J, Horlyck A, Osther PJ. Bosniak classification system: inter-observer and intra-observer agreement among experienced uroradiologists. Acta Radiol. 2015;56(3):374–83.

    Article  Google Scholar 

  25. Osman H, Yan JH, Chan J, Munir J, Alrasheed S, Krishna S, et al. Inter-observer and intra-observer agreement of Bosniak classification of cystic renal masses: comparison between original version to version 2019 and effect of an online support calculator. Can Urol Assoc J. 2021;15(12):420–2.

    Article  Google Scholar 

  26. Shampain KL, Shankar PR, Troost JP, Galantowicz ML, Pampati RA, Schoenheit TR, et al. Interrater agreement of Bosniak classification version 2019 and version 2005 for cystic renal masses at CT and MRI. Radiology. 2021;302(2):210853.

    Google Scholar 

  27. Tse JR, Shen J, Yoon L, Kamaya A. Bosniak classification version 2019 of cystic renal masses assessed With MRI. AJR Am J Roentgenol. 2020;215(2):413–9.

    Article  Google Scholar 

  28. Tse JR, Shen L, Shen J, Yoon L, Kamaya A. Prevalence of malignancy and histopathological association of Bosniak classification, version 2019 Class III and IV cystic renal masses. J Urol. 2021;205(4):1031–8.

    Article  Google Scholar 

  29. Salameh JP, McInnes MDF, McGrath TA, Salameh G, Schieda N. Diagnostic accuracy of dual-energy CT for evaluation of renal masses: systematic review and meta-analysis. AJR Am J Roentgenol. 2019;212(4):W100–5.

    Article  Google Scholar 

  30. Jung DC, Oh YT, Kim MD, Park M. Usefulness of the virtual monochromatic image in dual-energy spectral CT for decreasing renal cyst pseudoenhancement: a phantom study. AJR Am J Roentgenol. 2012;199(6):1316–9.

    Article  Google Scholar 

  31. Patino M, Prochowski A, Agrawal MD, Simeone FJ, Gupta R, Hahn PF, et al. Material separation using dual-energy CT: current and emerging applications. Radiographics. 2016;36(4):1087–105.

    Article  Google Scholar 

  32. Neville AM, Gupta RT, Miller CM, Merkle EM, Paulson EK, Boll DT. Detection of renal lesion enhancement with dual-energy multidetector CT. Radiology. 2011;259(1):173–83.

    Article  Google Scholar 

  33. Glomski SA, Wortman JR, Uyeda JW, Sodickson AD. Dual energy CT for evaluation of polycystic kidneys: a multi reader study of interpretation time and diagnostic confidence. Abdom Radiol (NY). 2018;43(12):3418–24.

    Article  Google Scholar 

  34. Meyer M, Nelson RC, Vernuccio F, Gonzalez F, Farjat AE, Patel BN, et al. Virtual unenhanced images at dual-energy CT: influence on renal lesion characterization. Radiology. 2019;291(2):381–90.

    Article  Google Scholar 

  35. Cha D, Kim CK, Park JJ, Park BK. Evaluation of hyperdense renal lesions incidentally detected on single-phase post-contrast CT using dual-energy CT. Br J Radiol. 2016;89(1062):20150860.

    Article  Google Scholar 

  36. Connolly MJ, McInnes MDF, El-Khodary M, McGrath TA, Schieda N. Diagnostic accuracy of virtual non-contrast enhanced dual-energy CT for diagnosis of adrenal adenoma: a systematic review and meta-analysis. Eur Radiol. 2017;27(10):4324–35.

    Article  Google Scholar 

  37. Siddaiah M, Krishna S, McInnes MDF, Quon JS, Shabana WM, Papadatos D, et al. Is Ultrasound useful for further evaluation of homogeneously hyperattenuating renal lesions detected on CT? AJR Am J Roentgenol. 2017;209(3):604–10.

    Article  Google Scholar 

  38. Atri M, Tabatabaeifar L, Jang HJ, Finelli A, Moshonov H, Jewett M. Accuracy of contrast-enhanced US for differentiating benign from malignant solid small renal masses. Radiology. 2015;276(3):900–8.

    Article  Google Scholar 

  39. Bertolotto M, Cicero C, Perrone R, Degrassi F, Cacciato F, Cova MA. Renal masses with equivocal enhancement at CT: characterization with contrast-enhanced ultrasound. AJR Am J Roentgenol. 2015;204(5):W557–65.

    Article  Google Scholar 

  40. Zarzour JG, Lockhart ME, West J, Turner E, Jackson BE, Thomas JV, et al. Contrast-enhanced ultrasound classification of previously indeterminate renal lesions. J Ultrasound Med. 2017;36(9):1819–27.

    Article  Google Scholar 

  41. Pacheco EO, Torres US, Alves AMA, Bekhor D, D’Ippolito G. Bosniak classification of cystic renal masses version 2019 does not increase the interobserver agreement or the proportion of masses categorized into lower Bosniak classes for non-subspecialized readers on CT or MR. Eur J Radiol. 2020;131: 109270.

    Article  Google Scholar 

Download references

Author information

Authors and Affiliations

  1. Medical Imaging Department, King Abdulaziz Medical City, Ministry of National Guard Health Affairs, Ar Rimayah, Riyadh, 14611, Saudi Arabia

    Sumaya Alrasheed

  2. Medical Imaging Department, King Salman Medical City, Medinah, Saudi Arabia

    Samah Faqeeh

  3. Department of Medical Imaging, The Ottawa Hospital, Ottawa, ON, Canada

    Nicola Schieda

Authors
  1. Sumaya Alrasheed
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Samah Faqeeh
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Nicola Schieda
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Sumaya Alrasheed.

Ethics declarations

Conflict of interest

All authors declare that they have no conflict of interest.

Additional information

Publisher's Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

This article is part of the Topical collection on Computed Tomography.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Alrasheed, S., Faqeeh, S. & Schieda, N. Bosniak Classification Version 2019: A CT-Based Update for Radiologists. Curr Radiol Rep 10, 83–92 (2022). https://doi.org/10.1007/s40134-022-00397-7

Download citation

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s40134-022-00397-7

Keywords

  • Bosniak classification
  • Cystic renal masses
  • CT
  • MRI
  • Bosniak Version 2019