Intraoperative imprint cytology for real-time assessment of surgical margins during partial nephrectomy: A comparison with frozen section.

Introduction: Partial nephrectomy (PN) is the standard therapy for small renal masses. Resection margin assessment continues to be a key issue during PN. Biopsy of the residual kidney and intraoperative gross pathological consultations are the most common methods today. Intraoperative imprint cytology (IC) examinations have been successfully used in other tumor entities to assess surgical margins. We aim to evaluate the diagnostic value of intraoperative IC for surgical margin assessment during PN.

Materials And Methods: In addition to routinely performed frozen-section (FS) analysis, intraoperative IC examinations were performed on 114 tumors, which were resected with PN in our department between 2005 and 2010. These 2 were then matched with final histopathological examination findings. Before FS, roll-off IC slides were obtained, air dried, and stained by Hemacolor quick staining. Both the pathologist and the cytologist were blinded to the findings.

Results: Our study included 29 women and 76 men. Of 331 IC slides, 317 (96%) contained sufficient diagnostic cells. IC revealed 21 tumors with positive resection margins. Of the 21 positive resection margins, 2 were false positives. IC showed a specificity of 98%, sensitivity of 100%, a positive predictive value of 90%, and negative predictive value of 100%. FS examinations revealed positive resection margins in 20 tumors. One of these 20 margins was false positive. Furthermore FS examination failed to diagnose a positive resection margin in 1 tumor. FS examination showed a specificity of 99% and sensitivity of 98% in assessing surgical margins with a positive predictive value of 95% and negative predictive value 98%.

Conclusion: IC examinations exhibit equivalent diagnostic value compared with FS analysis. IC is an inexpensive method with an ability to give rapid and highly accurate information. Like any cytological examination, there is interobserver variability. IC could be considered as an alternative to FS especially when the nature of resection margins is suspected but further investigations are necessary.