The effect of cryoablation on the histologic interpretation of intraoperative biopsy of small clear cell renal carcinoma and renal oncocytoma

Background and Purpose: We evaluated the effects of the first freeze-thaw cycle of cryoablation on Fuhrman grade, histology, and tumor architecture of small clear cell renal carcinomas and renal oncocytomas using an 18-gauge needle biopsy. Patients and Methods: Between August 2006 and June 2007, 11 patients underwent cryoablation for 14 renal neoplasms. A laparoscopic approach was employed using third-generation argon/helium cryotechnology. Biopsies were taken prior to and following the first freeze-thaw cycle. Each biopsy sample was semiquantitively evaluated for cytoplasmic fraying, nuclear hyperchromasia, nuclear breakdown, and tissue discohesion as well as Fuhrman grade and interpretability by a single pathologist. Results: Eighteen precryoablation and 15 post-first freeze biopsies were taken. A tissue diagnosis was rendered in 100% of 11 patients. Pathologic diagnosis following the first freeze-thaw cycle of cryotherapy, as compared with the pretreatment biopsy, was accurate in 10 (91%) cases. Neither of the two post-first freeze biopsies in the remaining patient rendered a diagnosis: one had an insufficient quantity of tissue and the second missed the tumor, abstracting benign renal tissue. There was no significant difference in cytoplasmic fraying (P = 0.30), nuclear hyperchromasia (P = 0.43), nuclear breakdown (P = 0.58), or tissue discohesion (P = 0.84) observed between biopsies taken before and after the first freeze-thaw cycle of cryoablation. In no case did we note a change in Fuhrman grade greater than 1. Conclusions: One cycle of cryoablation does not significantly alter the architecture or Fuhrman grade of biopsy tissue, thus allowing for another method to obtain sufficient histologic tissue when bleeding is minimal.