Intraoperative examination of the sentinel lymph node for breast carcinoma staging

Intraoperative pathologic examination of the sentinel lymph node (SLN) draining a primary breast carcinoma allows an SLN-positive patient to undergo complete axillary lymphadenectomy as part of the same surgical procedure. However, the optimal technique for rapid SLN assessment has not been determined. We reviewed our results with imprint cytology (IC) and frozen section (FS) examination of SLNs from 278 patients. Compared with H&E-stained paraffin sections, IC and FS had an overall accuracy of 93.2%. The false-reassurance rate (false-negative results/all negative results) was 8.4%. It correctly identified 98% of macrometastases but only 28% of micrometastases. There were no false-positive results. Compared with paraffin-section cytokeratin immunohistochemistry results, the IC-FS false-reassurance rate increased to 25.8%. The false-reassurance rate decreased with smaller primary tumor size (T1 vs T2/3) and ductal type, smaller diameter of the SLN (< or = 2.0 cm), and greater pathologist experience. IC combined with 2-level FS reliably identifies SLN macrometastases but commonly fails to detect SLN micrometastases. If SLN micrometastasis is used to determine the need for further lymphadenectomy, more sensitive intraoperative methods will be needed to avoid a second operation.