title: Hypoechoic normal renal sinus and renal pelvis tumors: sonographic differentiation.
abstract: OBJECTIVE
  To evaluate the sonographic findings of an unusually hypoechoic renal sinus that mimics a tumor in the renal pelvis or renal sinus.
  
  
  METHODS
  Sonographic scans of 7 patients with an unusually hypoechoic portion in the renal sinus were reviewed retrospectively. Computed tomography, excretory urography, or both confirmed all sinuses as normal. Five consecutive cases of renal pelvis tumors, which were detected on sonography initially in same period, were also reviewed to determine the differences between the 2 conditions. All cases were transitional cell carcinomas of the renal calyces. The images were analyzed for location, shape, margin, presence of posterior sonic attenuation, and associated findings such as caliectasis.
  
  
  RESULTS
  Sonographic findings noted in patients with hypoechoic normal renal sinuses were irregular and poorly defined margins (n = 7), a central and symmetric location in the renal sinus (n = 6), the presence of posterior sonic attenuation with nonvisualization of the posterior border of the lesion (n = 7), an unaffected peripheral hyperechoic renal sinus (n = 7), and traversing hilar vessels in the lesion on color Doppler sonography (n = 7). In contrast, renal pelvis tumors had a relatively well-defined margin (n = 4), an eccentric location in the renal sinus (n = 2), a partially or completely obliterated hyperechoic renal sinus (n = 2), a visible posterior margin (n = 5), no posterior shadowing (n = 5), vessel displacement by the mass on color Doppler sonography (n = 5), and associated caliectasis (n = 1).
  
  
  CONCLUSIONS
  By being familiar with the sonographic characteristics of a hypoechoic renal sinus, it can be differentiated from renal pelvis tumors, and unnecessary diagnostic workups can be avoided.
authors.affiliation: Department of Radiology, Institute of Radiation Medicine, Seoul National University College of Medicine, South Korea.
authors.forename: Chang Kyu
authors.initials: CK
authors.lastname: Seong
authors.forename: Seung Hyup
authors.initials: SH
authors.lastname: Kim
authors.forename: Jong Seok
authors.initials: JS
authors.lastname: Lee
authors.forename: Keon Ha
authors.initials: KH
authors.lastname: Kim
authors.forename: Jung Suk
authors.initials: JS
authors.lastname: Sim
authors.forename: Kee-Hyun
authors.initials: KH
authors.lastname: Chang
mesh_terms: D000328:Adult; D002295:Carcinoma, Transitional Cell / Q000000981:diagnostic imaging*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007680:Kidney Neoplasms / Q000000981:diagnostic imaging*; D007682:Kidney Pelvis / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D018615:Ultrasonography, Doppler, Color