Lymph Node Harvesting in Colorectal Carcinoma Using the Dyeing Method

Daojin Chen, Yuanyuang Chen, Yuanghua Yang

Department of Surgery, 3rd Affiliated Hospital, Hunan Medical University, ChangSha, China

Abstract

In a prospective research, we compared the dyeing method for methylene blue with the clearance technique in 21 operative specimens of colorectal carcinoma. The dyed mesocolon or mesorectum was initially dissected and all the lymph nodes identified were examined histologically. After fat clearance of the same specimen the mesocolorectum was dissected again and further lymph nodes were examined. The dissection of dyed specimen (dyeing method) produced a mean of 45.9 lymph nodes per specimen, and following fat clearance a further mean of 1.2 nodes per specimen were found. The dyeing method showed 12 specimens (57.1%) having lymph node metastases, and after fat clearance no further specimens were found to be lymph node positive. Therefore, there was no significant difference in the lymph node harvest obtained by either method. Moreover, the dyeing method was cheaper, easy to handle and enabled much speedier reporting.
In addition, the charts of 1076 consecutive colorectal carcinoma resections from 1993 to 1997 at 4 major hospitals of Hunan province were reviewed. In this prospective analysis, all lymph nodes were resected manually in a routine fashion. The mean number of lymph nodes recovered per specimen and the metastatic rate were 6.63 and 46.2%, much less than when using the dyeing method. Besides, the results show a strong positive association (p<0.005) between the proportion of specimens with metastases detected and the number of lymph nodes recovered. Thus, we believe pathologists and surgeons should retrieve all the lymph nodes that can be recovered and use the methylene blue dyeing method for picking up lymph nodes.