"Calculator: Bosniak classification (2019) online calculator"
"one or more enhancing nodule(s)"
"one or more enhancing nodule(s)"
"The proposed new version of Bosniak classification of cystic renal masses is the first major revision since the death of the American radiologist Morton Bosniak (1929-2016), who died three years earlier. Bosniak published the first iteration of his classification system in 1986 6."
"Calculator: Bosniak classification (2019) online calculator"
"Class I"
"Class II"
"Class IIF"
"Class III"
"Class IV"
"Class I"
"Class II"
"Class IIF"
"Class III"
"Class IV"
"Class I"
"Class II"
"Class IIF"
"Class III"
"Class IV"
"A 2023 validation study reported that using v2019 would have resulted in fewer benign cyst resections (by ~2%) and more cysts categorised as class III and class IV 13. It, however, reported a reduction in inter-observer agreement 13. This later finding was not replicated in a larger 2025 systematic review and meta-analysis, which found that the v2019 Bosniak classification provides better diagnostic specificity and also improved inter-rater reliability than the 2005 version 14. Using v2019 likely reduces overtreatment in the management of cystic renal masses 13,14."
Expected headings
"Classification"
"CT"
"MRI"
"Follow up"
"what constitutes "measurable enhancement" has not been formally defined in the 2019 version; in 2005 Bosniak stated that an increase of 20 HU or more at contrast-enhanced CT was likely enhancement, whilst 10-20 HU was indeterminate 2; another group suggested an increase of 15% signal intensity or more at contrast-enhanced MRI 8"
"what constitutes "measurable enhancement" has not been formally defined in the 2019 version; in 2005 Bosniak stated that an increase of 20 HU or more at contrast-enhanced CT was likely enhancement, whilst 10-20 HU was indeterminate 2; another group suggested an increase of 15% signal intensity or more at contrast-enhanced MRI 8"
"according to the Bosniak classification 2019, if the enhancing solid component volume of a renal cystic lesion is more than 25% of all mass volume, the Bosniak classification should not be used and the mass should be instead categorised as a solid renal mass with cystic/necrotic changes; because a solid renal cell carcinoma with cystic/necrotic changes has a poor prognosis compared to the renal cell carcinoma that is arising from a Bosniak class IV cystic renal mass 1"
"renal cyst-like lesions with an infectious, inflammatory and vascular aetiology should not be classified by the Bosniak system 1"