Abstract: Objective: We studied fresh mesenteric and mesorectal tissue after standard dissection of colorectal cancer specimens using a clearing method to evaluate lymph nodes (LN) that could have been missed.
Method: After traditional dissection, 50 consecutive unfixed residual mesenteric and mesorectal tissues were entirely managed by a new clearing solution, which incorporates hydrochloric acid obtaining a really good degree of fat dissolution, facilitating the identification of missed LNs.
Results: By fat clearance, 498 (mean per specimen, 10) additional LNs were found, most of them (83%) varying in size from 1 to 5?mm. and 22 (4.41%) LNs revealed tumour metastases. In two rectal carcinoma specimens that had been treated by neoadjuvant chemoradiotherapy, no LNs were found by traditional dissection; after checking by the clearing method, additional LNs were harvested in both. Three patients were reclassified and upstaged.
Conclusion: According to our findings, after standard dissection in the remaining mesentery of colorectal specimen there are missed positive LNs, which should be evaluated to avoid pathological understaging.