ABSTRACT
<p><b>OBJECTIVE</b>To investigate the feasibility of ex vitro sentinel lymph node (SLN) mapping with methylene blue staining and its clinical value of predicting regional lymph node metastasis in colorectal cancer.</p><p><b>METHODS</b>Methylene blue (1 ml) was injected submucosally around the tumor immediately after resection. After 2-5 minutes, the first blue-dyed lymph nodes, sentinel lymph nodes (SLNs), were harvested for pathological examination, and compared with the pathological results of other lymph nodes.</p><p><b>RESULTS</b>Of the total 32 patients, 57 SLNs were successfully identified in 30 patients with an average of 1.9 nodes per person. The successful labeling rate was 93.8% (30/32). Among the 13 patients with positive SLNs, there were 5 patients with positive non-SLNs and 8 patients with negative Non-SLNs. Among the 17 patients with negative SLNs, there were 15 patients with negative non-SLNs and 2 patients with positive Non-SLNs. The accuracy of SLNs for regional lymph node metastasis was 93.3% (28/30), the false negative rate was 11.8% (2/17), and the specificity was 100% (13/13).</p><p><b>CONCLUSIONS</b>Ex vitro sentinel lymph node mapping with methylene blue staining in colorectal carcinoma is technically feasible and can effectively reflect the metastatic situation of regional lymph nodes.</p>