EFFECT OF XYLENE CLEARANCE OF MESENTERIC FAT ON HARVEST OF LYMPH-NODES AFTER COLONIC RESECTION

Objective: To find out if clearance of surgical colectomy specimens wi th xylene gave a higher yield of lymph nodes and more accurate staging than the traditional step-sectioning technique. Design: Consecutive o pen study. Setting: Private hospital, United States. Material: 84 spec imens from colonic resections, 4 of which were total colectomies and t he remaining 80 segmental resections. Interventions: The first 41 (2 c olectomies and 39 segmental resections) were cleared by step-sectionin g alone (to establish baseline values). The remainder (n = 2 and 41, r espectively) were step-sectioned, the lymph nodes were removed, and th en the residual tissue was cleared with xylene. Main outcome measures: The number of lymph nodes found, and if the diagnosis was changed by the finding of additional nodes. Results: The baseline values in the t wo total colectomy specimens were 76 and 101, and the mean (range) aft er segmental colectomy was 21 (1-98). The values after total colectomy in the second group were 33 and 73, and after xylene clearance an add itional 12 and 17 nodes were found. After segmental colectomy a mean ( range) of 13 (0-43) was found, and an additional 4 (0-12) were found a fter xylene clearance. No additional nodes containing metastases were found in total colectomy specimens after xylene clearance, and only 6 additional nodes after segmental resection contained metastases. These changed the histological stage of the disease in only 2 patients. Con clusions: Xylene clearance offers little advantage over careful tradit ional step-sectioning of specimens, but may be of value if the histopa thologist does not do routine meticulous step-sectioning.