Abstract
BackgroundRenal angiomyolipoma without visible fat (RAML-wvf) and clear cell renal cell carcinoma (ccRCC) have many overlapping features on imaging, which poses a challenge to radiologists. This study aimed to create a scoring system to distinguish ccRCC from RAML-wvf using computed tomography imaging.MethodsA total of 202 patients from 2011 to 2019 that were confirmed by pathology with ccRCC (n=123) or RAML (n=79) were retrospectively analyzed by dividing them randomly into a training cohort (n=142) and a validation cohort (n=60). A model was established using logistic regression and weighted to be a scoring system. ROC, AUC, cut-off point, and calibration analyses were performed. The scoring system was divided into three ranges for convenience in clinical evaluations, and the diagnostic probability of ccRCC was calculated.ResultsFour independent risk factors are included in the system: 1) presence of a pseudocapsule, 2) a heterogeneous tumor parenchyma in pre-enhancement scanning, 3) a non-high CT attenuation in pre-enhancement scanning, and 4) a heterogeneous enhancement in CMP. The prediction accuracy had an ROC of 0.978 (95% CI, 0.956–0.999; P=0.011), similar to the primary model (ROC, 0.977; 95% CI, 0.954–1.000; P=0.012). A sensitivity of 91.4% and a specificity of 93.9% were achieved using 4.5 points as the cutoff value. Validation showed a good result (ROC, 0.922; 95% CI, 0.854–0.991, P=0.035). The number of patients with ccRCC in the three ranges (0 to <2 points; 2–4 points; >4 to ≤11 points) significantly increased with increasing scores.ConclusionThis scoring system is convenient for distinguishing between ccRCC and RAML-wvf using four computed tomography features.
Highlights
75% of renal cell carcinomas are clear cell renal carcinomas [1], the most common presentation of which is a renal mass
The inclusion criteria were: 1) patients who had a definitive pathologic diagnosis of either renal angiomyolipoma (RAML) or clear cell renal carcinomas (ccRCC), 2) patients underwent computed tomography (CT) and the image quality was satisfactory for analysis, 3) there was no visible fat on unenhanced CT images, and 4) patients did not receive chemotherapy or radiotherapy before the images were taken
Enhanced scanning was performed in three phases, including the post-contrast corticomedullary phase (CMP), post-contrast nephrographic phase (NP), and post-contrast excretory phase (EP)
Summary
75% of renal cell carcinomas are clear cell renal carcinomas (ccRCC) [1], the most common presentation of which is a renal mass. RAML can often be diagnosed due to macroscopic fat tissue within the tumor that can be detected by imaging. RAML-wvf mimics ccRCC on imaging due to the absence of fat, and is often diagnosed incorrectly [5]. This presents a difficult challenge to radiologists and clinicians; since misdiagnosis might cause harm for patients, diagnosis is typically confirmed through biopsy or surgery. Renal angiomyolipoma without visible fat (RAML-wvf) and clear cell renal cell carcinoma (ccRCC) have many overlapping features on imaging, which poses a challenge to radiologists. This study aimed to create a scoring system to distinguish ccRCC from RAML-wvf using computed tomography imaging
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