ABSTRACT
BACKGROUND: We recently introduced ex vivo, intra-arterial methylene blue injection as a simple method to improve the lymph node (LN) harvest in gastrointestinal cancer. We now combined it with a novel ex vivo sentinel lymph node (evSLN) mapping technique. METHODS: evSLN mapping was performed by subserosal (n = 20) or submucosal (n = 30) India ink injection. Subsequently, methylene blue was injected intra-arterially to enhance visibility of all LNs to improve the overall LN harvest. Manual LN dissection was carried out after fixing overnight. evSLNs nodes were identified by detecting carbon particles during histological examination. In primary node-negative cases, all detected LNs were step sectioned and immunohistochemically stained for pan-cytokeratin. RESULTS: India ink injection was easy to perform. Methylene blue injection failed in 1 case. The mean lymph node harvest was 42 ± 18 LNs, and the SLN detection rate was 78%. The sensitivity for detecting metastases was 75%. The mean SLN number was 3 ± 1. LN metastases were found in 20 of 47 malignant cases (43%). Skip metastases occurred in 4 cases. Of these cases, 3 showed involvement of at least 1 entire LN. True upstaging (N0 â N1mi) was found in 1 of 23 cases (4%) within a SLN after advanced evaluation. CONCLUSIONS: Combination of methylene blue technique and ex vivo sentinel mapping is feasible, easy to perform, and cost effective. It guarantees an optimal LN harvest and has the potential to heighten the sensitivity of metastasis detection.
Subject(s)
Adenocarcinoma/secondary , Adenoma/pathology , Colorectal Neoplasms/pathology , Methylene Blue , Sentinel Lymph Node Biopsy/methods , Adenocarcinoma/surgery , Adenoma/surgery , Colorectal Neoplasms/surgery , Coloring Agents/administration & dosage , Female , Humans , Injections, Intra-Arterial , Lymph Node Excision , Lymph Nodes/pathology , Lymphatic Metastasis , Male , Methylene Blue/administration & dosage , Middle Aged , Neoplasm Invasiveness , Prognosis , Prospective Studies , Sensitivity and Specificity , Survival RateABSTRACT
PURPOSE: The American Joint Committee on Cancer recommends examination of a minimum of 12 lymph nodes in rectal cancer for accurate staging. Despite this, several studies have demonstrated that nodal harvest is highly variable and often inadequate. This study was designed to determine if staining the nodes with methylene blue dye produced a better and more accurate harvest in comparison with standard pathologic lymph node dissection. METHODS: Fifty patients with primary resectable rectal cancer were randomly assigned to undergo a standard nodal harvest or a harvest after ex vivo injection of the inferior mesenteric artery with methylene blue. A fat clearance technique was subsequently used to identify the maximum possible number of lymph nodes and metastasis. RESULTS: The average lymph node harvest was 30 +/- 13.5 in the stained group and 17 +/- 11 in the unstained group (P < 0.001). At least 12 nodes were identified in every case in the stained group. In the unstained group, 7 of 25 cases (28 percent) did not meet the minimum criteria of 12 nodes (P < 0.01). Among the pathologists for the stained group, no difference was found in the harvest (P < 0.05), but variability was detected between the pathologists in the unstained group (P = 0.6). After fat clearance, one case in the unstained group was upstaged, whereas no cases in the stained group were upstaged. CONCLUSIONS: Staining the lymph nodes with methylene blue dye is an accurate staging technique and reliably produces an adequate harvest.
