The Predictive Power of Bosniak 3 and 4 Cystic Renal Lesion Categorization Using Contrast‐Enhanced Ultrasound

• Published in: Journal of ultrasound in medicine 2024-05, Vol.43 (5), p.933-949
• Main Authors: Járay, Ákos, Farkas, Péter István, Semjén, Dávid, Botz, Bálint
• Format: Article
• Language: English
• Subjects: Bosniak classification system; contrast‐enhanced ultrasound; renal cystic lesion
• ISSN: 0278-4297; 1550-9613
• DOI: 10.1002/jum.16424

Objectives Contrast‐enhanced ultrasound (CEUS) is increasingly utilized for the noninvasive assessment of renal cystic lesions, using the Bosniak grading system. Bosniak 3–4 lesions require surgical referral, which allows correlation with the histopathological outcome. Methods In this single‐center, retrospective study we evaluated renal CEUS exams conducted with SonoVue® with a diagnosis of a Bosniak 3 or 4 lesion between 2019 and 2022. A total of 49 patients and 50 lesions met the inclusion criteria, 31 lesions had available histopathological results. Patient demographics, cyst morphology, and dominant imaging features were registered. The histopathological diagnosis was considered a reference standard. Results Positive predictive power (PPV) for neoplastic lesions was comparable in the Bosniak 3 and 4 categories (75 vs 93.3%, P = .33), while PPV for histopathologically malignant lesion was considerably higher in the latter group (25 vs 93.33%, P = .0002). None of the lesions which had vividly enhancing thin septa as their dominant CEUS feature were malignant. Oncocytoma, multilocular cystic renal neoplasm of low malignant potential, and cystic nephroma were the major benign entities among Bosniak 3 lesions. Localized cystic kidney disease and hemorrhagic cysts were found to be the primary mimickers leading to false positive imaging findings. Conclusions CEUS has a high predictive power for malignancy in the Bosniak 4 category, which is not maintained in the Bosniak 3 group due to the large proportion of benign lesions. Adherence to rigorous rule‐in criteria and active surveillance strategies need to be considered for equivocal CEUS Bosniak 3 lesions. Access the CME test here and search by article title.