Application of ex vivo sentinel lymph node biopsy in the staging of colorectal cancer

    LIU Daª²Peng, ZHANG Yong, REN Hong, CHEN Wuª²Ke

    Department of Oncological Surgery, First Affiliated Hospital, Xi¬ðan Jiaotong University, Xi¬ðan 710061, China

    ¡¾Abstract¡¿ AIM: To explore whether ex vivo sentinel lymph node (SLN) biopsy can be easily applied in improving the accuracy of pathologic staging for colorectal cancer (CRC). METHODS: The specimens from 26 patients (14 males, 12 females) with CRC were freshly (within 5 min) delivered to pathological examination and underwent ex vivo SLN biopsy. SLNs were identified as the 1st to 4th blue stained nodes after ex vivo submucosal peritumoral injection of 10 g/L isosulfan blue (IB) dye. The SLNs were sectioned and examined histologically by HE staining. Additional immunohistochemical staining for cytokeratins was performed when blueª²stained lymph nodes were negative by HE staining. RESULTS: Of the 26 specimens, SLNs were identified by ex vivo SLN biopsy in 23 (88.5%). In the 11 cases where the SLNs were negative in HE staining for micrometastases and in immunohistochemical staining for cytokeratins, all other nonª²SLNs in the specimens were also negative (0% false negative rate). The SLN was positive for micrometastases by HE staining in only 8 (30.7%) cases; the other 4 (15.3%) cases with negative nodes by HE staining were demonstrated positive for micrometastases through immunohistochemical staining for cytokeratins. CONCLUSION: Ex vivo SLN biopsy mapping is a feasible technique for the staging of CRC, especially in combination with immunohistochemical staining for cytokeratins, which offers reference for the assisted chemotherapy of CRC patients. ......