Bosniak classification of cystic renal masses, version 2019: interpretation pitfalls and recommendations to avoid misclassification


The purpose of this review is to describe the potential sources of variability or discrepancy in interpretation of cystic renal masses under the Bosniak v2019 classification system. Strategies to avoid these pitfalls and clinical examples of diagnostic approaches are also presented. Potential pitfalls in the application of Bosniak v2019 are divided into three categories: interpretative, technical, and mass related. An organized, comprehensive review of possible discrepancies in interpreting Bosniak v2019 cystic masses is presented with pictorial examples of difficult clinical cases and proposed solutions. The scheme provided can guide readers to consistent, precise application of the classification system. Radiologists should be aware of the possible sources of misinterpretation of cystic renal masses when applying Bosniak v2019. Knowing which features and types of cystic masses are prone to interpretive errors, in addition to the inherent trade-offs between the CT and MR techniques used to characterize them, can help radiologists avoid these pitfalls.

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

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7
Fig. 8
Fig. 9
Fig. 10


  1. 1.

    Silverman SG, Pedrosa I, Ellis JH, et al. Bosniak Classification of Cystic Renal Masses, Version 2019: An Update Proposal and Needs Assessment. Radiology 2019; 292:475–488

    PubMed  PubMed Central  Article  Google Scholar 

  2. 2.

    Davies L, Petitti DB, Woo M, Lin JS. Defining, Estimating, and Communicating Overdiagnosis in Cancer Screening. Ann Intern Med 2018; 169:739

    PubMed  Article  PubMed Central  Google Scholar 

  3. 3.

    Esserman LJ, Thompson IM, Jr., Reid B. Overdiagnosis and overtreatment in cancer: an opportunity for improvement. JAMA 2013; 310:797–798

    CAS  PubMed  Article  Google Scholar 

  4. 4.

    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 American Journal of Roentgenology 2020;

  5. 5.

    Tse JR, Shen J, Yoon L, Kamaya A. Bosniak Classification Version 2019 of Cystic Renal Masses Assessed With MRI. AJR American journal of roentgenology 2020; 215:413–419

    PubMed  Article  Google Scholar 

  6. 6.

    Bai X, Sun SM, Xu W, et al. MRI-based Bosniak Classification of Cystic Renal Masses, Version 2019: Interobserver Agreement, Impact of Readers’ Experience, and Diagnostic Performance. Radiology 2020:200478

    Google Scholar 

  7. 7.

    Bosniak MA, Rofsky NM. Problems in the detection and characterization of small renal masses. Radiology 1996; 200:286–287

    CAS  PubMed  Article  Google Scholar 

  8. 8.

    Israel GM, Bosniak MA. Pitfalls in renal mass evaluation and how to avoid them. Radiographics 2008; 28:1325-1338

    PubMed  Article  Google Scholar 

  9. 9.

    Society of Abdominal Radiology Renal Cell Carcinoma Disease Focused Panel.

  10. 10.

    Jonisch AI, Rubinowitz AN, Mutalik PG, Israel GM. Can high-attenuation renal cysts be differentiated from renal cell carcinoma at unenhanced CT? Radiology 2007; 243:445–450

    PubMed  Article  Google Scholar 

  11. 11.

    Leao LRS, Mussi TC, Yamauchi FI, Baroni RH. Common pitfalls in renal mass evaluation: a practical guide. Radiol Bras 2019; 52:254–261

    PubMed  PubMed Central  Article  Google Scholar 

  12. 12.

    Ho VB, Allen SF, Hood MN, Choyke PL. Renal masses: quantitative assessment of enhancement with dynamic MR imaging. Radiology 2002; 224:695–700

    PubMed  Article  Google Scholar 

  13. 13.

    Birnbaum BA, Maki DD, Chakraborty DP, Jacobs JE, Babb JS. Renal cyst pseudoenhancement: evaluation with an anthropomorphic body CT phantom. Radiology 2002; 225:83–90

    PubMed  Article  Google Scholar 

  14. 14.

    Maki DD, Birnbaum BA, Chakraborty DP, Jacobs JE, Carvalho BM, Herman GT. Renal cyst pseudoenhancement: beam-hardening effects on CT numbers. Radiology 1999; 213:468–472

    CAS  PubMed  Article  Google Scholar 

  15. 15.

    Patel J, Davenport MS, Khalatbari S, Cohan RH, Ellis JH, Platt JF. In vivo predictors of renal cyst pseudoenhancement at 120 kVp. AJR American Journal of Roentgenology 2014; 202:336–342

    PubMed  PubMed Central  Article  Google Scholar 

  16. 16.

    Hindman NM. Approach to Very Small (< 1.5 cm) Cystic Renal Lesions: Ignore, Observe, or Treat? AJR American Journal of Roentgenology 2015; 204:1182–1189

  17. 17.

    Tu W, Alzahrani A, Currin S, et al. Evaluation of a free-breathing respiratory-triggered (Navigator) 3-D T1-weighted (T1W) gradient recalled echo sequence (LAVA) for detection of enhancement in cystic and solid renal masses. Eur Radiol 2019; 29:2507–2517

    PubMed  Article  PubMed Central  Google Scholar 

  18. 18.

    Israel GM, Hindman N, Bosniak MA. Evaluation of cystic renal masses: comparison of CT and MR imaging by using the Bosniak classification system. Radiology 2004; 231:365–371

    PubMed  Article  PubMed Central  Google Scholar 

  19. 19.

    Zhong J, Cao F, Guan X, Chen J, Ding Z, Zhang M. Renal cyst masses (Bosniak category II-III) may be over evaluated by the Bosniak criteria based on MR findings. Medicine (Baltimore) 2017; 96:e9361

    Article  Google Scholar 

  20. 20.

    Weibl P, Klatte T, Kollarik B, et al. Interpersonal variability and present diagnostic dilemmas in Bosniak classification system. Scand J Urol Nephrol 2011; 45:239–244

    PubMed  Article  Google Scholar 

  21. 21.

    Krishna S, Murray CA, McInnes MD, et al. CT imaging of solid renal masses: pitfalls and solutions. Clin Radiol 2017; 72:708–721

    CAS  PubMed  Article  Google Scholar 

  22. 22.

    McGahan JP, Sidhar K, Fananapazir G, et al. Renal cell carcinoma attenuation values on unenhanced CT: importance of multiple, small region-of-interest measurements. Abdom Radiol (NY) 2017; 42:2325–2333

    Article  Google Scholar 

  23. 23.

    Padole A, Ali Khawaja RD, Kalra MK, Singh S. CT radiation dose and iterative reconstruction techniques. AJR American Journal of Roentgenology 2015; 204:W384–392

    PubMed  Article  Google Scholar 

  24. 24.

    Geyer LL, Schoepf UJ, Meinel FG, et al. State of the Art: Iterative CT Reconstruction Techniques. Radiology 2015; 276:339–357

    PubMed  Article  Google Scholar 

  25. 25.

    Silverman SG, Israel GM, Herts BR, Richie JP. Management of the incidental renal mass. Radiology 2008; 249:16–31

    PubMed  Article  Google Scholar 

  26. 26.

    Israel GM, Bosniak MA. How I do it: evaluating renal masses. Radiology 2005; 236:441–450

    PubMed  Article  Google Scholar 

  27. 27.

    Sahni VA, Silverman SG. Imaging management of incidentally detected small renal masses. Semin Intervent Radiol 2014; 31:9–19

    PubMed  PubMed Central  Article  Google Scholar 

  28. 28.

    Adey GS, Pedrosa I, Rofsky NM, Sanda MG, DeWolf WC. Lower limits of detection using magnetic resonance imaging for solid components in cystic renal neoplasms. Urology 2008; 71:47–51

    PubMed  Article  Google Scholar 

  29. 29.

    Udare A, Abreu-Gomez J, Krishna S, McInnes M, Siegelman E, Schieda N. Imaging Manifestations of Acute and Chronic Renal Infection That Mimics Malignancy: How to Make the Diagnosis Using Computed Tomography and Magnetic Resonance Imaging. Can Assoc Radiol J 2019; 70:424–433

    PubMed  Article  Google Scholar 

  30. 30.

    Andrew B. Rosenkrantz BWM, Elie Portnoy, Jonathan Melamed, Samir S.Taneja, Natasha E.Wehrlia. Impact of size of region-of-interest on differentiation of renal cell carcinoma and renal cysts on multi-phase CT: Preliminary findings. European Journal of Radiology 2014; 83:239–244

  31. 31.

    Mullett R, Belfield JC, Vinjamuri S. Calyceal diverticulum - a mimic of different pathologies on multiple imaging modalities. J Radiol Case Rep 2012; 6:10–17

    PubMed  PubMed Central  Google Scholar 

  32. 32.

    O’Connor SD, Pickhardt PJ, Kim DH, Oliva MR, Silverman SG. Incidental finding of renal masses at unenhanced CT: prevalence and analysis of features for guiding management. AJR American journal of roentgenology 2011; 197:139–145

    PubMed  Article  Google Scholar 

  33. 33.

    Pooler BD, Pickhardt PJ, O’Connor SD, Bruce RJ, Patel SR, Nakada SY. Renal cell carcinoma: attenuation values on unenhanced CT. AJR American Journal of Roentgenology 2012; 198:1115–1120

    PubMed  Article  Google Scholar 

  34. 34.

    Schieda N, Vakili M, Dilauro M, Hodgdon T, Flood TA, Shabana WM. Solid Renal Cell Carcinoma Measuring Water Attenuation (-10 to 20 HU) on Unenhanced CT. AJR American journal of roentgenology 2015; 205:1215–1221

    PubMed  Article  Google Scholar 

  35. 35.

    Kim NY, Lubner MG, Nystrom JT, et al. Utility of CT Texture Analysis in Differentiating Low-Attenuation Renal Cell Carcinoma From Cysts: A Bi-Institutional Retrospective Study. AJR American journal of roentgenology 2019; 213:1259–1266

    PubMed  Article  Google Scholar 

  36. 36.

    Webster WS, Thompson RH, Cheville JC, Lohse CM, Blute ML, Leibovich BC. Surgical resection provides excellent outcomes for patients with cystic clear cell renal cell carcinoma. Urology 2007; 70:900–904; discussion 904

  37. 37.

    Park SY, Shin SJ, Cho NH, et al. Solid Small Renal Mass Without Gross Fat: CT Criteria for Achieving Excellent Positive Predictive Value for Renal Cell Carcinoma. AJR American journal of roentgenology 2018; 210:W148–W155

    PubMed  Article  Google Scholar 

  38. 38.

    Hartman DS, Davis CJ, Jr., Johns T, Goldman SM. Cystic renal cell carcinoma. Urology 1986; 28:145–153

    CAS  PubMed  Article  Google Scholar 

  39. 39.

    Oliva MR, Glickman JN, Zou KH, et al. Renal cell carcinoma: t1 and t2 signal intensity characteristics of papillary and clear cell types correlated with pathology. AJR American journal of roentgenology 2009; 192:1524–1530

    PubMed  Article  Google Scholar 

  40. 40.

    Adams LC, Bressem KK, Jurmeister P, et al. Use of quantitative T2 mapping for the assessment of renal cell carcinomas: first results. Cancer Imaging 2019; 19:35

    PubMed  PubMed Central  Article  Google Scholar 

  41. 41.

    Cornelis F, Helenon O, Correas JM, et al. Tubulocystic renal cell carcinoma: a new radiological entity. Eur Radiol 2016; 26:1108–1115

    CAS  PubMed  Article  Google Scholar 

  42. 42.

    Mnatzakanian GN, Shinagare AB, Sahni VA, Hirsch MS, Silverman SG. Early-stage clear cell tubulopapillary renal cell carcinoma: imaging features and distinction from clear cell and papillary subtypes. Abdom Radiol (NY) 2016; 41:2187–2195

    Article  Google Scholar 

  43. 43.

    Cheon PM, Rebello R, Naqvi A, Popovic S, Bonert M, Kapoor A. Anastomosing hemangioma of the kidney: radiologic and pathologic distinctions of a kidney cancer mimic. Curr Oncol 2018; 25:e220–e223

    CAS  PubMed  PubMed Central  Article  Google Scholar 

  44. 44.

    Paschall AK, Nikpanah M, Farhadi F, et al. Hereditary leiomyomatosis and renal cell carcinoma (HLRCC) syndrome: Spectrum of imaging findings. Clin Imaging 2020; 68:14–19

    PubMed  Article  Google Scholar 

  45. 45.

    Kim E, Zschiedrich S. Renal Cell Carcinoma in von Hippel-Lindau Disease-From Tumor Genetics to Novel Therapeutic Strategies. Front Pediatr 2018; 6:16

    PubMed  PubMed Central  Article  Google Scholar 

  46. 46.

    Ristau BT, Kamat SN, Tarin TV. Abnormal Cystic Tumor in a Patient with Hereditary Leiomyomatosis and Renal Cell Cancer Syndrome: Evidence of a Precursor Lesion? Case Rep Urol 2015; 2015:303872

    PubMed  PubMed Central  Google Scholar 

  47. 47.

    Wang SS, Gu YF, Wolff N, et al. Bap1 is essential for kidney function and cooperates with Vhl in renal tumorigenesis. Proc Natl Acad Sci U S A 2014; 111:16538–16543

    CAS  PubMed  PubMed Central  Article  Google Scholar 

  48. 48.

    Chahoud J, McGettigan M, Parikh N, et al. Evaluation, diagnosis and surveillance of renal masses in the setting of VHL disease. World J Urol 2020;

  49. 49.

    Hyder A Omer MRH. Primary Renal Lymphoma. Nephrology 2007; 12:314–315

    Article  Google Scholar 

  50. 50.

    Natalya Hakim M, Yevgen Chornenkyy, Shadi Qasem. Malignant Perivascular Epithelioid Cell Tumor Mimicking Renal Cell Carcinoma: A Diagnostic Pitfall. American Journal of Clinical Pathology 2019; 152:S62

  51. 51.

    Cyriac S RR, Shirley S, Sagar GT. Primary renal lymphoma mimicking renal cell carcinoma. Indian J Urol 2010; 26:441–443

    PubMed  PubMed Central  Article  Google Scholar 

Download references


This work was partially supported by NIH Grant R01CA154475 (IP).

Author information




EE, NC, SK, NS and IP performed the literature search and drafted the manuscript. MSD, NH, SS, and IP critically revised the manuscript and contributed case examples.

Corresponding author

Correspondence to Elizabeth Edney.

Ethics declarations

Conflict of interest

Matthew S. Davenport receives royalties from Wolters Kluwer and Ivan Pedrosa received an honorarium from Bayer Healthcare and has received stock options from Health Tech International. He also has institutional research agreements with Philips Healthcare and with Siemens Healthcare. Ivan Pedrosa serves on the Scientific Advisory Board for Bayer Healthcare and is a Scientific Advisor for Health Tech International. He has also been a Co-inventor of patents (no royalties received) for Philips Healthcare. Other authors have no disclosures.

Additional information

Publisher's Note

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

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Edney, E., Davenport, M.S., Curci, N. et al. Bosniak classification of cystic renal masses, version 2019: interpretation pitfalls and recommendations to avoid misclassification. Abdom Radiol (2021).

Download citation


  • Renal cell carcinomas
  • Cysts
  • Kidney
  • Diagnostic error
  • Magnetic resonance imaging
  • Kidney neoplasms