Morphological criteria for metastatic mesorectal lymph nodes in rectal cancer.
OBJECTIVE
Preoperative diagnostic criteria for mesorectal lymph node metastasis in rectal cancer patients were not consistent in previous reports. This study was conducted to get conclusions on this controversial issue by detailed histological examination.


METHODS
Fifty-eight patients with rectal carcinoma who underwent total mesorectal excision were studied. The total number of lymph nodes evaluated was 538. Parameters of lymph nodes evaluated were size, shape and texture of internal structure. Size was evaluated using long and short axis diameter. Shape was categorized into ovoid or irregular. Heterogeneity of internal structure was categorized into 4 groups (none, less than half, half or over, and whole) according to the tumor volume in the lymph node.


RESULTS
Of 538 lymph nodes, 118 lymph nodes were found to have metastasis. There was a significant difference in terms of long (6.6 vs. 3.5 mm: p < 0.05) and short axis diameters (5.1 vs. 2.6 mm: p < 0.05) between metastatic and non-metastatic lymph nodes. Shape showed significantly higher proportion of irregularity (26% vs. 11%) in the metastasis group, while ovoid shape was still the majority in both groups. Heterogeneity of internal structure was significantly more frequent in the metastasis group. In the ROC curve analysis, heterogeneity of internal structure showed the highest diagnostic accuracy (Area under ROC curve, AUC: 0.998), followed by long axis diameter (AUC: 0.794), short axis diameter (AUC: 0.821) and shape of lymph nodes (AUC: 0.570). Multivariate analysis showed that presence of heterogeneity (odds ratio 1.442, p < 0.00001), long axis diameter (odds ratio 1.082, p = 0.001) and short axis diameter (odds ratio 1.068, p = 0.037) were the independent signs of lymph node metastasis.


CONCLUSIONS
The current histological study confirmed that presence of heterogeneity of internal structure, long axis diameter, and short axis diameter were the independent findings for mesorectal lympnode metastasis in rectal cancer patient.
Matsuoka
Hiroyoshi
H
Department of Surgery and Pathology, Kyorin University, School of Medicine, Tokyo, Japan. hmatsu@ks.kyorin-u.ac.jp
Masaki
Tadahiko
T
Kobayashi
Takaaki
T
Sato
Kazunori
K
Sugiyama
Masanori
M
Atomi
Yutaka
Y
Ohkura
Yasuo
Y
D019540:Area Under Curve; D006801:Humans; D008198:Lymph Nodes / Q000473:pathology*; D008207:Lymphatic Metastasis; D015999:Multivariate Analysis; D012372:ROC Curve; D012004:Rectal Neoplasms / Q000473:pathology*