title: Accuracy of diagnosis by guided biopsy of renal mass lesions classified indeterminate by imaging studies.
abstract: OBJECTIVE
  To define the accuracy, safety, and impact of percutaneous biopsies of indeterminate mass lesions as an additional diagnostic tool. The vast majority of renal mass lesions are routinely diagnosed by radiographic features alone. However, with the increased use of computed tomography scanning and ultrasound, many smaller renal masses, which are "indeterminate" (refractory to categorization on the basis of imaging alone), are now being discovered.
  
  
  METHODS
  We retrospectively reviewed 583 patients (364 male and 219 female) with indeterminate renal mass lesions diagnosed by imaging studies that were further investigated by percutaneous biopsy. Patients were followed up for at least 5 years if the biopsy result demonstrated a benign lesion, or they underwent surgical exploration if the biopsy result demonstrated a malignancy. Biopsy or aspiration material was assessed by histopathologic and cytologic evaluation and, when appropriate, with biochemistry, Gram stain, culture, and sensitivity. The biopsy site was localized by computed tomography, ultrasound, or fluoroscopy.
  
  
  RESULTS
  Five hundred eighty-three patients with indeterminate renal mass lesions (representing 7.2% of all renal masses diagnosed from 1967 through 1996) were diagnosed by imaging studies complemented by guided biopsy. Sixty-six patients were lost to follow-up, leaving 517 patients who were analyzed. In 393 cases (76%), the imaging-guided biopsy provided a definitive diagnosis. The incidence of false diagnoses was 1.2% (7 biopsies). In 124 of the cases (21%), imaging-guided biopsy was unable to determine the etiology of the lesion with acceptable confidence; of these, 21 biopsies did not provide enough material to establish the diagnosis (16.9%).
  
  
  CONCLUSIONS
  Overall, percutaneous biopsy of the kidney has proved to be a safe and accurate diagnostic procedure, with impact on the management of cystic or solid renal lesions.
authors.affiliation: Section of Urology, Department of Surgery, University of Medicine and Dentistry New Jersey Medical School, Newark, New Jersey 07103, USA.
authors.forename: F
authors.initials: F
authors.lastname: Richter
authors.forename: N G
authors.initials: NG
authors.lastname: Kasabian
authors.forename: R J
authors.initials: RJ
authors.lastname: Irwin
authors.forename: R A
authors.initials: RA
authors.lastname: Watson
authors.forename: E K
authors.initials: EK
authors.lastname: Lang
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001707:Biopsy, Needle / Q000379:methods; D003951:Diagnostic Errors; D005260:Female; D005471:Fluoroscopy; D006801:Humans; D007668:Kidney / Q000473:pathology*; D007674:Kidney Diseases / Q000175:diagnosis; D008297:Male; D008875:Middle Aged; D015641:Radiography, Interventional; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed; D018084:Ultrasonography, Interventional