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Lymph node revealing solution and traditional 10% buffered formaldehyde for detecting lymph nodes in colorectal
1Department of Pathology, Taichung Veterans General Hospital, Taiwan, ROC.
Background:
Cancer stage has been the most important factor in evaluating the prognosis and treatment of colorectal carcinoma, and the presence of lymph node metastasis in the resected specimen plays a key role in serial staging. We evaluated a newly proposed "lymph node revealing solution" (LNRS) that proponents claim is inexpensive, easy, rapid, and innocuous, and that could help to establish the stage of disease more accurately than buffered formaldehyde (formalin). Our study compared traditional 10% formalin and LNRS as second search solutions to determine whether LNRS is a more useful and practical solution than formalin.
Methods:
Thirty randomly selected colorectal carcinomas from low anterior resection (LAR) were studied. The specimens were handled routinely on the first day. Then, the entire fat of odd-numbered cases was immersed in three times its volume of LNRS, and the entire fat of even-numbered cases was immersed in 10 times its volume of formalin overnight. The chi-squared test was used to evaluate the results.
Results:
Of 145 cassettes in the second search by LNRS, seven had no lymph nodes. Of 107 cassettes in the second search by formalin, 18 had no lymph nodes. Totally, 792 lymph nodes were found with an average number of 26.4 per case and 1.53/cm (per centimeter of specimen) in all 30 cases. By the LNRS method, 138 lymph nodes were found in the 15 odd-numbered cases, and by the formalin method, 89 lymph nodes were found in the 15 even-numbered cases. We were able to adjust the stage upward in two cases by LNRS-fixation method. There were no changes in staging in the formalin-fixation method cases.
Conclusions:
LNRS showed no statistically significant difference from formalin in the numbers of total lymph nodes, positive lymph nodes, or minute (less than 1 mm) lymph nodes found. Nonetheless, we do believe that LNRS is a potential replacement solution for formalin due to its fast fixation, ease of searching, high identification rate and time-saving procedure.