Intraoperative assessment of sentinel node using imprint cytology

Sentinel lymph node (SLN) biopsy has replaced axillary sampling as the axillary staging procedure of choice in patients with breast cancer. Accurate intraoperative evaluation of the SLN would allow axillary lymph node clearance to be performed during the initial operation when the SLN is positive for metastatic disease. The aim of the present study was to assess the accuracy of intraoperative imprint cytology (IC) of the SLN in two different institutions in the United Kingdom.

All breast cancer patients who underwent a SLN biopsy using a standard protocol in two hospital breast units were included. The SLN was sent fresh to the pathology laboratory, where it was immediately processed and examined by a cytopathologist using IC. The intraoperative IC results were compared with the final histopathological results. No therapeutic decisions were made based on the results of IC in this study.

A total of 166 patients were included, with 47 positive and 119 negative cases on final histology. Of the 47 patients who were positive on final histology, there were 29 positive and 18 negative cases on IC (sensitivity = 61.7%). All 119 patients who were negative on final histology were negative on IC (specificity, 100%). The negative and positive predictive value of the final histology was 86.9% and 100%, respectively. The accuracy of IC was 89.2%.

The results from these two breast units are comparable with findings reported in the published literature, confirming that IC can be used to assess SLN biopsy intraoperatively. No unnecessary axillary node clearance would have been carried out based on the results of IC.