Intraoperative cytologic evaluation of sentinel lymph nodes in patients with breast carcinoma by scrape preparation

Intraoperative evaluation of sentinel lymph nodes (SLNs) in patients with breast carcinoma allows surgeons to complete axillary lymph node dissection in one procedure if any SLN shows metastasis. The accuracy of intraoperative pathological diagnosis is critical for decision-making. The purpose of this study was to evaluate our rapid intraoperative cytologic diagnosis of SLN through comparing with the final surgical pathologic diagnosis of the corresponding lymph nodes. A total of 454 SLNs from 159 consecutive female patients with a preoperative diagnosis of breast carcinoma over 3-year period were included in this study. After gross examination of each bisected lymph node, a scrape preparation was prepared for each submitted lymph node and was stained by the rapid Papanicolaou method. The intraoperative cytologic diagnosis was compared with the final surgical pathologic diagnoses. The overall sensitivity of intraoperative cytology was 52.5% with specificity of 100%. There were 17 false-negative cases. Of them, six nodes had isolated tumor cells, seven nodes had micrometastasis (0.2-2 mm), and four nodes had macrometastasis (>2 mm). There were no interpretive errors identified. The size of metastasis and tumor grade appeared to be significant factors in detecting metastasis by cytology. In addition, subsequent non-SLN involvement was 9% in patients with micrometastasis versus 50% in patients with macrometastasis (P < 0.05). Our study shows that the intraoperative cytologic evaluation of SLNs in breast carcinoma is a reasonably accurate method. The majority of false-negative cases were due to micrometastasis and isolated tumor cells.