title: Early-stage clear cell tubulopapillary renal cell carcinoma: imaging features and distinction from clear cell and papillary subtypes.
abstract: 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).
  
  
  
  This IRB-approved retrospective study included 54 stage T1a 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.
  
  
  
  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 ill-defined margin (p = 0.003), and demonstrated nonenhancing areas (p = 0.0003). The presence of all three of these statistically significant features [hypoattenuation (unenhanced attenuation ≤25 HU), 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.
  
  
  
  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.
authors.affiliation: Department of Radiology, Brigham and Women's Hospital, 75 Francis St, Boston, MA, 02115, USA. mnatzakanian@smh.ca.|Department of Medical Imaging, St. Michael's Hospital, 3-141CC, 30 Bond St., Toronto, ON, M5B 1W8, Canada. mnatzakanian@smh.ca.
authors.forename: Gevork N
authors.initials: GN
authors.lastname: Mnatzakanian
authors.affiliation: Department of Radiology, Brigham and Women's Hospital, 75 Francis St, Boston, MA, 02115, USA.|Dana-Farber Cancer Institute, 450 Brookline Ave, Boston, MA, 02215, USA.
authors.forename: Atul B
authors.initials: AB
authors.lastname: Shinagare
authors.affiliation: Department of Radiology, Brigham and Women's Hospital, 75 Francis St, Boston, MA, 02115, USA.
authors.forename: V Anik
authors.initials: VA
authors.lastname: Sahni
authors.affiliation: Department of Pathology, Brigham and Women's Hospital, 75 Francis St., Amory-3, Boston, MA, 02115, USA.
authors.forename: Michelle S
authors.initials: MS
authors.lastname: Hirsch
authors.affiliation: Department of Radiology, Brigham and Women's Hospital, 75 Francis St, Boston, MA, 02115, USA.
authors.forename: Stuart G
authors.initials: SG
authors.lastname: Silverman
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002291:Carcinoma, Papillary / Q000000981:diagnostic imaging* / Q000473:pathology*; D002292:Carcinoma, Renal Cell / Q000000981:diagnostic imaging* / Q000473:pathology*; D003287:Contrast Media; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007680:Kidney Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D009367:Neoplasm Staging; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed
chemical_list: D003287:Contrast Media
keywords: CT and MRI features; Clear cell tubulopapillary renal cell carcinoma; Renal cell carcinoma subtype; Renal mass