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Diagnostic Accuracy of Contrast-Enhanced Ultrasound in Differentiating RCC from AML in Small Hyperechoic Renal Masses (≤ 3 cm): A Retrospective Single-Center Study

Year: 2025

Type: article

Abstract: BACKGROUND: Small (≤ 3 cm) hyperechoic renal masses are challenging to characterize due to overlapping features between angiomyolipomas (AMLs) and renal cell carcinomas (RCCs). Contrast-enhanced ultrasound (CEUS) offers a noninvasive alternative, particularly when CT or MRI are inconclusive or contraindicated. This study assessed CEUS diagnostic accuracy in differentiating RCC from AML and identified predictive enhancement patterns. METHODS: In this retrospective single-center study, 104 patients with incidentally detected small hyperechoic renal masses underwent CEUS between December 2021 and July 2024. Two blinded radiologists independently assessed wash-in and wash-out dynamics, peak intensity, homogeneity, and perilesional rim-like enhancement. Histopathology was obtained when available; lesions with ≥ 18 months of stable imaging follow-up were considered benign. Diagnostic metrics, interobserver agreement (ICC), and multivariate logistic regression (IBM SPSS Statistics 29.0) were used to identify independent predictors, reported as odds ratios (ORs) with 95% confidence intervals (CIs). RESULTS: Of 104 lesions, 80 were classified as AMLs and followed with ultrasound, while 28 were biopsied, confirming 26 RCCs (papillary 53%, chromophobe 32%, clear cell 15%) and 2 atypical AMLs. Rapid wash-out (sensitivity = 84%, specificity = 91%, AUC = 0.90) and perilesional rim-like enhancement (specificity = 95%, PPV = 90%) were the strongest CEUS predictors of RCC. Multivariate analysis identified rapid wash-out (OR = 5.0; 95% CI, 2.0-12.0) and perilesional enhancement (OR = 3.8; 95% CI, 1.5-10.0) as independent predictors. Combined CEUS features achieved an AUC = 0.93. Interobserver agreement was good (ICC 0.75-0.9). CONCLUSION: CEUS accurately differentiates RCC from AML in small hyperechoic renal masses. Rapid wash-out and perilesional rim-like enhancement are independent predictors of malignancy and may guide biopsy versus surveillance decisions.

Source: Clinical Genitourinary Cancer

DOI: 10.1016/j.clgc.2025.102414