title: Prevalence and predictors of benign lesions in renal masses smaller than 7 cm presumed to be renal cell carcinoma.
abstract: The present study was designed to determine the incidence and predictive factors of benign renal lesions in 450 patients who underwent surgical removal of solitary renal masses <7 cm in diameter. Of the 450 renal masses, 88 (19.9%) were benign lesions. Female sex, nephron-sparing surgery, surgery between 1990 and 1996, cystic components on imaging, and small tumors (<4 cm) were independently associated with benign pathology.
  
  
  OBJECTIVE
  To determine the association between preoperative parameters with final benign pathology in patients who underwent surgical removal of solitary renal masses <7 cm in diameter.
  
  
  METHODS
  A database of 450 patients without metastatic disease who underwent radical nephrectomy or nephron-sparing surgery (NSS) for removal of renal masses <7 cm between January 1990 and December 2009 was reviewed. Age, sex, symptoms, year and type of surgery, solid or cystic appearance, and tumor size were analyzed as presumed predictors of benign pathology. Multivariate analysis was performed to identify parameters associated with benign pathology.
  
  
  RESULTS
  In all, 88 (19.9%) of the tumors were benign, including 39 (8.7%) oncocytomas and 22 (4.9%) angiomyolipomas. The benign lesion rate for tumors ≤2, 2.1-4, and 4.1-7 cm was 30.3%, 27.1%, and 12.5%, respectively (2P < .001). For the periods of 1990-1996, 1997-2003, and 2004-2009, the frequency of benign tumors was 25%, 17.3%, and 18.4% (2P = .271), the incidental tumor rate was 48.1%, 60.4%, and 63.8% (2P = .027), mean tumor size was 5, 4.6, and 4.1 cm (2P < .001), and the NSS rate was 28.8%, 43.2%, and 52.7% (2P < .001), respectively. Logistic regression analysis revealed that female sex, NSS, surgery between 1990 and 1996, cystic components on imaging, and small tumors (<4 cm) based on radiologic examination were independently associated with benign pathology (odds ratio [OR] = 3.26, 2.56, 2.43, 2.41, and 1.96, respectively).
  
  
  CONCLUSIONS
  The incidence of incidental and small tumors amenable to NSS increased over time. Female sex was the strongest predictor of benign pathology.
authors.affiliation: Hacettepe University, School of Medicine, Department of Urology, Ankara, Turkey. blntakdogan@yahoo.com
authors.forename: Bulent
authors.initials: B
authors.lastname: Akdogan
authors.forename: Ahmet
authors.initials: A
authors.lastname: Gudeloglu
authors.forename: Kubilay
authors.initials: K
authors.lastname: Inci
authors.forename: Levent Mert
authors.initials: LM
authors.lastname: Gunay
authors.forename: Artan
authors.initials: A
authors.lastname: Koni
authors.forename: Haluk
authors.initials: H
authors.lastname: Ozen
mesh_terms: D000328:Adult; D000368:Aged; D002292:Carcinoma, Renal Cell / Q000453:epidemiology / Q000473:pathology* / Q000601:surgery; D005260:Female; D006801:Humans; D033162:Incidental Findings; D007680:Kidney Neoplasms / Q000453:epidemiology / Q000473:pathology* / Q000601:surgery; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009392:Nephrectomy; D016017:Odds Ratio; D015995:Prevalence; D012189:Retrospective Studies; D047368:Tumor Burden