Development of a clinical prediction model for assessment of malignancy risk in Bosniak III renal lesions, "Beyond the Abstract," by Ajit H. Goenka, MD and Erick M. Remer, MD

BERKELEY, CA ( - Renal cystic lesions are being detected with escalating frequency due the increasing use of cross-sectional abdominal imaging. The Bosniak classification system is well established and widely used by both referring physicians and radiologists for risk-stratification and management of renal cystic lesions. In this system, Bosniak III (BIII) category includes renal cystic lesions that have thickened, have irregular or smooth walls, or have septa with measurable enhancement.

Clinical uncertainty is engendered by the imaging identification of a Bosniak III (BIII) renal lesion as the malignancy rate is commonly considered to be 50%. Pre-operative assessment of malignancy risk would be useful for patient counseling, risk stratification, and clinical assessment of the need for surgical treatment versus imaging surveillance. Thus, the purpose of our study was to identify independent predictors of malignancy in BIII lesions, and to build a prediction model based on readily identifiable clinical variables.

To the best of our knowledge, the 107 BIII lesions in 101 patients analyzed in our study is the largest series of surgically excised BIII lesions reported in literature. Our findings indicate that clinical risk factors offer modest, but definite predictive ability for malignancy in BIII lesions. In our study, smaller lesion size, obesity and a personal history of RCC were found to be independent risk factors for malignancy in patients with BIII lesions. In fact, lesion size was found to be the strongest predictor of malignant potential. This finding may appear counter-intuitive. It should be noted that a direct relationship between lesion size and malignancy is well accepted for solid renal masses. On the other hand, lesion size is not taken into consideration in the Bosniak classification of cystic renal lesions. We hypothesize that the difference in relationship between lesion size and its malignant potential for solid and cystic renal lesions may be due to differences in the contents of the cystic lesions. Benign cystic lesions contain more epithelial tissue, which may contribute to their larger size over a period of time, on account of the secreted fluid component. On the other hand, malignant cystic lesions may not attain large sizes due to proportionately greater neoplastic tissue.

There is potential to refine and possibly improve the accuracy of the prediction model developed in our study. The approaches that we suggest include incorporation of individual imaging features that go into classifying renal cystic lesions and integration of biomarkers obtained through percutaneous sampling in patients who undergo biopsy. Development of accurate prediction models is critical given the prevailing uncertainties in the management of BIII lesions.

Written by:
Ajit H. Goenka and Erick M. Remer as part of Beyond the Abstract on This initiative offers a method of publishing for the professional urology community. Authors are given an opportunity to expand on the circumstances, limitations etc... of their research by referencing the published abstract.

Cleveland Clinic, Cleveland, OH USA

Development of a clinical prediction model for assessment of malignancy risk in Bosniak III renal lesions - Abstract

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