[Mediastinal lymph node metastasis from esophageal carcinoma: CT assessment with pathologic correlation]

Computed tomographic (CT) scans were performed in 179 patients with esophageal carcinoma to evaluate mediastinal lymph node metastasis. Histopathologic findings were compared with CT findings in a total of 7,218 resected lymph nodes. First, the criterion for lymph node metastasis on CT scans was 10 mm or more in long transverse diameter. The overall sensitivity and positive predictive value (PPV) were 19% (60 of 317 nodes) and 33% (60 of 180 nodes), respectively. Analysis of each of the eight subgroups of mediastinal nodes revealed that the PPV was more than 70% in node Nos. 105, 108, 110, and 112. In other subgroups, however, the PPV was less than 60%. Sensitivity was less than 50% in all eight subgroups. Second, the criterion for metastasis was 10 mm or more in short transverse diameter. The overall sensitivity and PPV were 8% (26 of 317 nodes) and 63% (26 of 41 nodes), respectively. Analysis of subgroups showed that the PPV in No. 106 nodes increased to 92%. In No. 106 nodes, use of a 5 mm criterion in long transverse diameter increased sensitivity to only 55%. Of the 317 histopathologically proven metastatic lymph nodes, 90 nodes (28%) were 10 mm or more in size, 112 (35%) were 5-10 mm, and 115 (36%) were less than 5 mm. Of the 6,901 non-metastatic lymph nodes, 473 nodes (7%) were 10 mm or more in size. Small (less than 5 mm in size) metastatic nodes were present in all eight subgroups. Among No. 107 and 109 nodes, large (10 mm or more in size) nonmetastatic nodes were prominent, resulting in low sensitivity and PPV. We conclude that CT does not provide an accurate assessment of metastatic versus non-metastatic mediastinal lymph nodes in patients with esophageal carcinoma.