Early-stage clear cell tubulopapillary renal cell carcinoma: imaging features and distinction from clear cell and papillary subtypes

Abstract

Purpose: Clear cell tubulopapillary renal cell carcinoma (CCTPRCC) is a recently described, low grade subtype of renal cancer. We determined if imaging features could be used to distinguish early-stage CCTPRCC from stage-matched clear cell RCC (ccRCC) and papillary RCC (pRCC). Subjects and Methods:This IRB-approved retrospective study included 54 stage-Ia patients with pathologically-confirmed CCTPRCC (n=18), ccRCC (n=18), and pRCC (n=18). CT (n=48) and MRI (n=27) exams were reviewed and imaging features compared. Continuous variables were evaluated using ANOVA and Tukey's multiple comparison tests. Categorical variables were compared using Chi square test or Fisher's exact test.Results: Compared to pRCC, CCTPRCC had a lower mean attenuation value on unenhanced CT (p<0.017), was more often hyperintense on T2-weighted images (p<0.0001), showed an illdefined margin (p=0.003), and demonstrated nonenhancing areas (p=0.0003). The presence of all three of these statistically significant features (hypoattenuation [unenhanced attenuation < 25HU], ill-defined margin, nonenhancing areas) yielded an area under the Receiver Operator Curve (ROC) of 0.92 (95% CI: 0.83-0.99) for differentiating CCTPRCC from pRCC. There were no significant differences in the imaging features of CCTPRCC and ccRCC. Conclusions:Early stage clear cell tubulopapillary renal cell carcinoma can be distinguished from papillary RCC based on low attenuation on unenhanced CT, high intensity on T2-weighted images, an ill-defined margin, and presence of nonenhancing areas, but cannot be distinguished from clear cell RCC. Author ManuscriptClick here to view linked References 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 CCTPRCC is now considered the fourth most common variant of RCC, behind ccRCC (70%), pRCC (16.6%), and chromophobe carcinoma (5.9%), with an incidence of 4.1% [1][2][3][4][5][6].CCTPRCC was reported initially in patients with end-stage renal disease, however, the majority of subsequent cases are now known to occur sporadically [1][2][3][5][6][7][8][9]. The average age at presentation is 60 and there is no sex predilection [1,2,8,9].There is limited literature on the biologic behavior of CCTPRCC, however, prior reports suggest that these neoplasms behave indolently, and carry a favorable prognosis [1][2][3][4][7][8][9][10]. To our knowledge, metastases have not been reported [1][2][3][4][7][8][9][10][11]. Therefore, the prospective differentiation of CCTPRCC from the more common subtypes such as clear cell RCC (ccRCC) and papillary RCC (pRCC) at an early stage may be useful for counseling patients on prognosis and treatment plans. For example, an active surveillance approach may be considered in a patient with CCTPRCC [12].To our knowledge, no prior study has attempted to differentiate CCTPRCC from other renal cell tumor subtypes ...

Computed tomography imaging characteristics of clear cell papillary renal cell carcinoma

“…In this study, CCP RCC was associated with ESRD in two patients who were submitted to hemodialysis, consistent with other studies ( 9 , 16 ). As noted previously, CCP RCC was initially reported in patients with ESRD, but was later observed in non-disease settings.…”

“…They found that compared to papillary RCC, CCP RCC has a lower mean attenuation value on unenhanced CT (≤25HU), ill-defined margins, non-enhancing areas, and hyperintensity on T2-weighted magnetic resonance imaging. However, the authors noted no significant differences in imaging features between CCP RCC and clear cell RCC (9). In the present study, a pathological analysis of CCP RCC revealed proliferating cells with clear cytoplasm that formed papillo-tubular, acinar, and cystic architectures, as described in the ISUP (1).…”

“…They found that compared to papillary RCC, CCP RCC has a lower mean attenuation value on unenhanced CT (≤25HU), ill-defined margins, non-enhancing areas, and hyperintensity on T2-weighted magnetic resonance imaging. However, the authors noted no significant differences in imaging features between CCP RCC and clear cell RCC ( 9 ).…”

Current Challenges in Diagnosis and Assessment of the Response of Locally Advanced and Metastatic Renal Cell Carcinoma

“…This subtype is thought to have a low potential for malignancy and a favorable prognosis (25,26). A broad spectrum of imaging features has been described, including a predominantly complex cystic appearance and a predominantly solid heterogeneous or homogeneous mass, with hypo-and hyperenhancing solid areas, which make it challenging to differentiate clear cell papillary RCC from papillary RCC and clear cell RCC at imaging (27,28).…”