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.