Possibility of pre-operative diagnosis of lymph node metastasis based on morphology.

BACKGROUND/AIMS: The accuracy of pre-operative diagnosis of lymph node metastasis is insufficient. Our aim was to define the possibility of diagnosing metastatic lymph nodes based on morphology.

METHODOLOGY: One hundred and fifty-seven patients with pre-operatively untreated esophageal squamous cell carcinoma underwent resection, 5334 lymph nodes were isolated, and the short and long diameters were measured. We tried to construct a linear regression line for metastasis rate versus lymph node size (long diameter classified at intervals of 1 mm) by each location. The ratio of short diameter to long diameter (SL ratio) of metastasis-positive lymph nodes was compared with that of negative ones at each location.

RESULTS

Gradient and intercept of overall regression line was 0.0213 and 0.0101, respectively, and the long diameter producing a metastasis rate of 80% (LD80) was 37.1 mm. Metastasis-positive lymph nodes larger than calculated LD80 represented no more than 9.5% of all the corresponding metastasis-positive nodes. The locations with significant difference of SL ratio between metastasis-positive and negative ones were limited to right cardiac, left gastric artery, thoracic paratracheal, bifurcation, and the highest mediastinal nodes.

CONCLUSIONS

There is a low possibility that lymph node metastasis can be exactly diagnosed pre-operatively based on the size and morphology.