Cytology as an Alternative to Frozen Section at the Time of Nephron-sparing Surgery to Evaluate Surgical Margin Status

Abstract

To evaluate quick-staining cytology as an alternative method to intraoperative frozen sectioning after nephron-sparing nephrectomy. Eighty-two partial nephrectomies were performed with intraoperative quick-staining cytology and frozen section evaluation. The results of both were compared with permanent histology as the gold standard. After partial nephrectomy, permanent histologic surgical margins were positive in 8 of 82 (9.7%), cytology in 10 of 82 (12%), and frozen sectioning in 4 of 82 (5%). In comparison with permanent histologic examination, sensitivity of the cytologic examination was 87.5%, positive predictive value 70%, specificity 95.9%, and negative predictive value 98.6%. Kappa values (κ) revealed a good level of agreement between intraoperative cytology and final histologic examination (κ = 0.751; P <.0001). In comparison with permanent histology, sensitivity of frozen sections was 50%, specificity 100%, positive predictive value 100%, and negative predictive value 95%. Of the 8 cases with positive margin on permanent histologic examination, 7 were cytologically positive and only 4 positive on frozen sectioning. Two patients had a local recurrence on follow-up, of which both were correctly identified on quick-staining cytology. The quick-staining cytologic evaluations were completed in <4 minutes. Quick-staining cytology is rapid, highly sensitive, and specific to evaluate intraoperative surgical margins at partial nephrectomy. It reduces diagnostic time, could be used as alternative to intraoperative frozen section, and warrants further investigation.