Axillary sentinel lymph node biopsy (SLNB) has become the standard of care for T1-2, N-0, M-0 carcinoma of the breast. However, the accuracy of frozen section in the intra-operative examination of sentinel nodes (SN) remains controversial. The senior author has championed the use of the intraoperative examination of SN by frozen section ex-amination from the inception of its use, and we present our experience with frozen section examination of SN, confirming that this technique is both practical and highly accurate.
Materials & Methods:
Between 2000 and 2007, 236 SLNB procedures were performed that were read as “fro-zen section negative.” SN were identified by 1% lymphazurin blue dye only. The identification of SN in these 236 women was 100%. Each SN specimen was prosected by the senior author; a dedicated surgical pathology technician prepared the frozen sections. Nodes were dissected from the specimen individually and cut at 2.5 to 3.0 mm. intervals. Each of these sections was then cut at three levels. The frozen sections were read by the attending pathologist assigned to frozen sections for that day, not by a dedicated breast pathologist. During the period of the study, 14 different attending pathologists read the slides, with 6 pathologists each reading more than 20 cases. Others read from 1 to14 cases.
In this group of 236 cases, 11 patients had positive nodes on subsequent examination of the H&E slides; thus, the false negative rate of intraoperative frozen section was 4.7%, i.e., the frozen section was read as negative but the paraffin sections were posi-tive for metastasis. Therefore, the sensitivity of the negative frozen section was >95%. Nine of the 11 false positives were micrometastases, less than 2 mm diameter, one was considered a macrometastasis, with two areas in one node measuring 2.0 and 2.1 mm each, and one was a sub-micrometastasis. The following variables were compared for significance: Pathologist, nuclear grade, histologic grade, margins, lymphovascular invasion, tumor type (ductal vs lobular), ER & PR values. The only significant variables were lymphovascular invasion (p=.019) and presence of in situ ductal carcinoma (p=.001). Only one of the false negatives was a purely lobular carcinoma (1/11).
Our data confirm the high accuracy of intraoperative examination of SN, >95%, even without a dedicated breast pathologist reviewing the sections. The missed metastases are likely to be micrometastases, and the likelihood of missing a macrometastasis is <1%. In patients with large primary tumors, presence of in situ ductal carcinoma or if lymphovascular invasion is associated with the tumor, special care should be taken to review these cases more thoroughly since these characteristics of tumors seem to make them more likely than others to have micrometastases to the axillary nodes over-looked.
Recommended CitationSchwartz, Gordon F.; Krill, Lauren S.; Palazzo, Juan P.; and Dasgupta, Abhijit, "The Value of Intraoperative Examination of Axillary Sentinel Nodes in Carcinoma of the Breast." (2008). Department of Pathology, Anatomy and Cell Biology Faculty Papers. Paper 22.