Comparison of two core biopsy techniques before and after laparoscopic cryoablation of small renal cortical neoplasms.
BACKGROUND
Cryoablation is an acceptable treatment option for small renal cortical neoplasms (RCN). Unlike extirpative interventions, intraoperative needle biopsy is the only pathologic data for ablated tumors. It is imperative that sampled tissue accurately captures pathology.  We studied the optimal intraoperative needle core biopsy protocol for small RCN during laparoscopic renal cryoablation (LCA).


METHODS
Patients with RCN<4cm underwent intraoperative biopsy during LCA. Four biopsy cores were taken per tumor, 2 before and 2 after LCA by using both  a standard and modified technique. Standard technique: needle biopsy device was deployed after insertion into the renal tissue at a depth of 5mm. Modified technique: needle biopsy device was deployed 1mm outside of the renal tissue. Biopsies were examined and compared with reference standard  pathology. Percentage agreement was calculated across biopsy types (standard vs. modified) and time points (pre- vs. postcryoablation). Logistic regression was used to identify factors impacting biopsy accuracy.


RESULTS
Thirty patients with 33 RCNs underwent LCA. The mean patient  age was 69.1±8.0yrs, and mean tumor size was 2.3±0.7cm. No significant bleeding resulted from biopsies. A definitive diagnosis was made in 31/33 RCNs (94.0%). Ten tumors (30.3%) were benign, 21 (63.7%) were malignant, and 2 (6.0%) were nondiagnostic. Biopsy length was significantly  longer using the standard vs. modified technique with mean lengths of 9.3mm vs. 7.0mm, respectively (P=.02). Highest agreement was seen in preablation biopsies (90.3%). A significant association with agreement was seen for younger age (P=.05) and larger tumor size (P=.02).


CONCLUSIONS
Younger age and larger tumor size were associated with improved accuracy. Preoperative sampling resulted in superior accuracy and the standard technique resulted in significantly longer cores. Use of preablation standard biopsy technique may result in the most accurate pathologic diagnosis  for patients undergoing cryoablation for small RCNs.
Department of Urology, University of California, San Francisco, CA, USA.
Matthew D
MD
Truesdale
Adam C
AC
Mues
Samantha
S
Sartori
Cristin N
CN
Casazza
Gregory W
GW
Hruby
Lara R
LR
Harik
Kathleen M
KM
O'Toole
Ketan K
KK
Badani
Alberto
A
Pérez-Lanzac
Jaime
J
Landman
D000368:Aged; D001707:Biopsy, Needle / Q000379:methods*; D003452:Cryosurgery / Q000379:methods*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007430:Intraoperative Care; D007672:Kidney Cortex / Q000473:pathology / Q000601:surgery; D007680:Kidney Neoplasms / Q000473:pathology* / Q000601:surgery*; D010535:Laparoscopy / Q000379:methods*; D016015:Logistic Models; D008297:Male; D011446:Prospective Studies; D016896:Treatment Outcome