Accuracy of intraoperative imprint cytology of sentinel lymph nodes in breast cancer

Background In breast cancer treatment, immediate completion of axillary lymph node dissection (ALND) can be performed if the intraoperative sentinel lymph node (SLN) examination is positive. This study evaluates the accuracy of intraoperative imprint cytology (IC) for detecting SLN metastases. Methods Pathology reports from 385 SLN biopsy examinations were reviewed retrospectively. The SLNs were serially sectioned perpendicular to the long axis and IC was performed intraoperatively. The SLNs then were formalin-fixed for permanent sections. Final pathology was compared with the intraoperative IC results. Results The sensitivities for IC detection of N0(i+) (n = 36), N1mi (n = 24), and N1a-3a (n = 65) metastases were 0%, 4%, and 74%, respectively. The specificity was 100%. Conclusions Final pathology identified 89 (23%) patients with N1 or greater disease. IC allowed 49 (55%) of these patients to undergo synchronous completion of ALND. No unnecessary completion ALNDs were performed. The sensitivity of IC decreased with decreasing size of the metastasis.