title: Centrally infiltrating renal masses on CT: differentiating intrarenal transitional cell carcinoma from centrally located renal cell carcinoma.
abstract: OBJECTIVE
  The objective of our study was to retrospectively determine the accuracy of CT for differentiating intrarenal transitional cell carcinoma (TCC) from centrally located renal cell carcinoma (RCC) and to define the most discriminating diagnostic CT features.
  
  
  METHODS
  CT studies of 98 pathologically proven central renal tumors (64 centrally located RCCs and 34 intrarenal TCCs) seen over 5 years at three university hospitals were reviewed by five specialty-trained radiologists who were blinded to the final diagnosis. Multiple CT features and global impression were graded on a 4-point score. The sensitivity and specificity of each feature and of global assessment were calculated and compared using receiver operating characteristic (ROC) analysis. Interobserver agreement (kappa values) was also calculated for each parameter.
  
  
  RESULTS
  All five readers recognized intrarenal TCCs with a high diagnostic accuracy (sensitivity, 90%; specificity, 90%; area under ROC curve [AUC], 0.80-0.95 for global assessment) with moderate-to-excellent interobserver agreement (κ = 0.72-1). Six CT features were most diagnostically specific for identifying intrarenal TCCs: tumor centered within the collecting system; focal filling defect in the pelvicalyceal system; preserved renal shape; absence of cystic or necrotic change; homogeneous tumor enhancement; and tumor extension toward the ureteropelvic junction (sensitivity, 68-82%; specificity, 79-89%; AUC, 0.75-0.84). There was moderate-to-good agreement among the readers over all these features (κ = 0.44-0.69).
  
  
  CONCLUSIONS
  Intrarenal TCC can be recognized with a high accuracy on CT; global impression showed the best diagnostic performance. A solid, homogeneously enhancing mass that is centered on the collecting system and extends toward the ureteropelvic junction combined with a focal pelvicalyceal filling defect and preserved renal outline is more likely to be an intrarenal TCC than a centrally located RCC.
authors.affiliation: Department of Clinical Radiology, St. George's Hospital, London, United Kingdom. arsalanraza@gmail.com
authors.forename: Syed Arsalan
authors.initials: SA
authors.lastname: Raza
authors.forename: Syed Aslam
authors.initials: SA
authors.lastname: Sohaib
authors.forename: Anju
authors.initials: A
authors.lastname: Sahdev
authors.forename: Nishat
authors.initials: N
authors.lastname: Bharwani
authors.forename: Susan
authors.initials: S
authors.lastname: Heenan
authors.forename: Hema
authors.initials: H
authors.lastname: Verma
authors.forename: Uday
authors.initials: U
authors.lastname: Patel
mesh_terms: D000328:Adult; D000368:Aged; D002292:Carcinoma, Renal Cell / Q000000981:diagnostic imaging*; D002295:Carcinoma, Transitional Cell / Q000000981:diagnostic imaging*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007680:Kidney Neoplasms / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*