Anatomic Study of Distribution, Numbers, and Size of Lymph Nodes in Mesorectum in Indians: A Autopsy Study

Abstract

This study was conducted to find the number, size, and distribution of the lymph nodes in the mesorectum in fresh cadavers without rectal cancer in Indians and to compare fat clearance method versus manual dissection of lymph nodes in terms of efficacy of lymph node yield. Thirty fresh cadavers underwent total mesorectal excision (TME) by midline incision. TME specimen was divided transversely (upper, middle, and lower thirds), and then further divided radially into 4 equal areas and the right lateral, left lateral, and posterior areas were taken for lymph node harvesting. In the first 15 cases (group A), lymph nodes were dissected manually from each of 9 areas. Number and diameters of harvested nodes were noted, and specimens were histopathologically examined. In the next 15 cases (group B), fat clearing technique was used, and the procedure was repeated. Mean number of lymph nodes recovered per cadaver was 6.2 (SD = 1.3; range, 5 to 9, group A = 5.86 ± 1.24, group B = 6.60 ± 1.29, P = .126) and mean size of the lymph node was 2.1 mm (SD = 0.38; range, 2 to 8 mm). Size and numbers of nodes in all the areas were similar between the 2 groups except in lower third, where smaller nodes were identified in greater numbers in group B. Manual dissection is an effective technique for node harvesting after TME, except for very small nodes found in the lower third of mesorectum. Accurate pathological examination of TME specimen is mandatory to avoid understaging of disease.