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Background: In early-stage endometrial cancer, intraoperative examination of sentinel lymph nodes (SLNs) can predict nodal involvement and avoid a second surgical procedure. Our goal was to determine the diagnostic accuracy (DA) of intraoperative examination in diagnosing metastatic pelvic SLNs., Methods: This was a retrospective study, including 125 patients with early stage endometrial cancer. Results of intraoperative examination by frozen section (FS) or imprint cytology (IC) were compared with final histology (serial sectioning and immunohistochemistry (IHC)). The diagnostic value of intraoperative examination was calculated., Results: Of the 111 patients with SLNs detected (89%), 87 (78.5%) had an intraoperative examination (30 with FS and 57 with IC). Intraoperative examination detected SLN metastases in 9 of 16 patients with metastatic SLN at definitive histology (sensitivity = 56.3%): macrometastasis in 8 and micrometastasis in 1. Seven false-negative cases were found (43.7%; micrometastases in 6 and isolated tumor cells in 1). The DA of intraoperative examination was 92% (95% confidence interval (CI), 84-96.7). For FS and IC, DA was 97.3% (95% CI, 85.8-99.9) and 88% (95% CI, 75.7-95.5), respectively., Conclusions: FS has better DA than IC for intraoperative examination of SLNs in endometrial cancer. The main limitation of both techniques is in detecting micrometastasis and isolated tumor cells.

Background: One of the problems of sentinel lymph node (SLN) biopsy is the risk of false negatives. At the Institut Curie, to reduce the false-negative rate, we have developed a histological quality control of the SLN performed by blue dye alone, which consists of verification of the SLN blue stain by the pathologist., Methods: A total of 324 patients underwent an SLN biopsy procedure with patent blue dye only followed by an immediate axillary dissection. Initially, SLNs were checked to ensure that they were blue by macroscopic examination. Finally, a search for immunohistochemistry micrometastasis was performed., Results: In 277 (85.5%) of 324 patients, an SLN was identified by the surgeon. After standard examination, the false-negative rate was 11.1% (10 of 90). After macroscopic checking of the 197 negative SLNs, 167 of the 197 were confirmed blue, and there were 5 false negatives, which brought the false-negative rate down to 5.6% (5 of 90). Sixty SLNs out of the 167 confirmed blue SLNs were then proved to be immunohistochemically micrometastatic, and there were 3 false negatives, giving a final false-negative rate of 2.2% (2 of 90; P =.002)., Conclusions: In this series, the procedure of pathologic analysis of the SLN has resulted in a significant reduction of the false-negative rate.