Differentiation, with multiphase CT, of clear cell renal cell carcinoma and papillary renal cell carcinoma, two distinct histological types, "Beyond the Abstract," by David Laszlo Tarnoki, MD, et al

BERKELEY, CA (UroToday.com) - Conventional clear cell (ccRCC) and papillary renal cell carcinoma (pRCC) have different behavioral characteristics and clinical management strategies (nephrectomy vs. nephron-sparing surgery). We aimed to retrospectively analyze the tumor attenuation characteristics in ccRCC and pRCC comparing the attenuation of the normal renal cortex in multiphase computed tomography (CT) using a standardized protocol to investigate the possible diagnostic criteria for preoperative differentiation. Quadriphasic multidetector CT images (unenhanced, corticomedullary, nephrographic, and excretory phases) of 20 histologically confirmed ccRCC and 15 pRCC patients (mean ages, 62.3±14.1 and 61.4±13.7 years, respectively) were analyzed retrospectively. The attenuation characteristics were compared with the attenuation of the normal renal cortex using either multiple 10-mm2 regions of interest (ROI) or whole tumor attenuation measurements. The degree of contrast enhancement was also compared. Univariate analysis revealed that ccRCC lesions showed higher mean attenuation values on the corticomedullary and nephrographic phases compared with pRCC masses (p < 0.05) using both measurement techniques. Accordingly, pRCC generally appeared as a less enhancing lesion compared with the normal renal cortex, and ccRCC appeared more hyperdense than pRCC in these two phases.

These findings underscore the importance of multiphase CT in the differentiation of these two subtypes of RCC, using standard assessment techniques based on the different contrast enhancement on the corticomedullary and nephrographic phases. The significant attenuation differences may be explained by the vascularization characteristics: ccRCC is known to display improved vascularization, whereas pRCC is typically a hypovascular mass. Differentiating between the two renal malignancies is essential because of their different therapeutic management strategies and behaviors. Because pRCC is related to better prognosis, a minimally invasive strategy (e.g., transcatheter embolization, cryotherapy, or radiofrequency ablation) can be chosen, and total nephrectomy can be avoided (nephron-sparing surgery). Additionally, nephron-sparing surgical techniques for pRCC provide an appropriate preoperative staging. Accordingly, measurement of the degree of enhancement on contrast-enhanced multidetector CT may be a simple and useful method to radiologically differentiate between the two histological types of RCC.

The major limitation of the study is that the number of renal carcinomas, especially that of pRCC, was insufficient for analysis of CT features, although they were comparable to those in previous investigations. Second, our analysis was retrospective, and the study population was limited to patients with preoperative multiphase CT examination, a fact that could have biased the selection of both conventional ccRCC and pRCC subjects.

Written by:
Pal Bata,a Janos Gyebnar,a David Laszlo Tarnoki,a Adam Domonkos Tarnoki,a Dora Kekesi,a Attila Szendroi,a Bence Fejer,a A. Marcell Szasz,c Peter Nyirady,b Kinga Karlinger,a and Viktor Berczia as part of Beyond the Abstract on UroToday.com. 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.

aDepartment of Radiology and Oncotherapy, Semmelweis University School of Medicine, Budapest, Hungary
bDepartment of Urology, Semmelweis University School of Medicine, Budapest, Hungary
cSecond Department of Pathology, Semmelweis University School of Medicine, Budapest, Hungary

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Clear cell renal cell carcinoma and papillary renal cell carcinoma: Differentiation of distinct histological types with multiphase CT - Abstract

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