title: Absence of viable renal carcinoma in biopsies performed more than 1 year following radio frequency ablation confirms reliability of axial imaging.
abstract: OBJECTIVE
  Radio frequency ablation is an emerging nephron sparing treatment option in select patients with small renal tumors. Some have questioned the completeness of cell death and the reliability of axial imaging for radio frequency ablation followup. We present results in patients with no evidence of radiographic active disease who underwent biopsy more than 1 year following ablation.
  
  
  METHODS
  Patients who had no clinical evidence of disease, defined as absent lesion growth and contrast enhancement on computerized tomography, 1 year or more following radio frequency ablation underwent percutaneous renal biopsy to evaluate cell viability in the ablative zone. A total of 19 patients (20 lesions) were included in the study. Histological comparison of pre-ablation and post-ablation specimens was performed using hematoxylin and eosin staining.
  
  
  RESULTS
  Pre-ablation biopsies confirmed that 17 of 20 tumors were renal cell carcinoma, while the remaining 3 were oncocytoma. Following ablation at a mean followup of 26.9 months (range 13.1 to 58.0) all 20 lesions were stable in size without evidence of contrast enhancement on computerized tomography. At repeat biopsy all histology specimens showed unequivocal tumor eradication with no evidence of cellular viability. Histological changes beyond 1 year demonstrated coagulative necrosis, hyalinization, inflammatory cell infiltration and residual ghost cells.
  
  
  CONCLUSIONS
  Pathological examination of radiographically negative lesions biopsied more than 1 year following radio frequency ablation confirmed no evidence of disease in all specimens. Therefore, axial imaging can reliably monitor treatment efficacy in the long term. Chronic changes after radio frequency ablation demonstrate coagulative necrosis and nonviable cells. This suggests an evolution of pathological changes that renders early post-ablative biopsy unreliable.
authors.affiliation: Department of Urology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9110, USA.
authors.forename: Jay D
authors.initials: JD
authors.lastname: Raman
authors.forename: Joshua M
authors.initials: JM
authors.lastname: Stern
authors.forename: Ilia
authors.initials: I
authors.lastname: Zeltser
authors.forename: Wareef
authors.initials: W
authors.lastname: Kabbani
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Cadeddu
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001706:Biopsy; D002292:Carcinoma, Renal Cell / Q000473:pathology* / Q000628:therapy*; D017115:Catheter Ablation; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007680:Kidney Neoplasms / Q000473:pathology* / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D013997:Time Factors