For educational and reference use only. These calculators do not replace clinical judgement, local protocols, or a qualified clinician. Verify every result independently before it informs patient care.
Body imaging
Bosniak Classification (2019)
Bosniak Classification of cystic renal masses, version 2019 (CT/MRI). Select the single most concerning feature: the most aggressive feature determines the class.
Result
Bosniak I
Malignancy ~0%, no malignant class I mass in the pooled series. Benign simple cyst, no follow-up.
Formula
Class = the single most aggressive feature present: I (simple) < II (few thin septa) < IIF (many thin, or 3 mm, enhancing) < III (≥4 mm / irregular enhancing) < IV (enhancing nodule).
References
- Silverman SG, et al. Bosniak Classification of Cystic Renal Masses, Version 2019. Radiology 2019;292:475–488.
- McGrath TA, et al. Proportion of malignancy in Bosniak classification of cystic renal masses version 2019 (v2019) classes: systematic review and meta-analysis. Eur Radiol 2023;33(2):1307–1317.
Disclaimer
A simplified single-feature selector for the 2019 update. Apply the full CT/MRI criteria (dedicated contrast phases, measurements, enhancement thresholds); the most aggressive feature governs the class. Two sets of proportions are given: the ones v2019 itself states, and the ones measured in pathology-confirmed masses (McGrath 2023). The second set is higher because only masses that went to surgery appear in it. Most class II and IIF masses never do.
For educational and reference use only. These calculators do not replace clinical judgement, local protocols, or a qualified clinician. Verify every result independently before it informs patient care.
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