Obscuration of the medial wall of the right bronchus in the assessment of subcarinal lymph node enlargement

The most sensitive sign in the detection of subcarinal lymphadenopathy is obscuration of the external surface of the medial wall of the right main bronchus (EWRB). This sign, however, has poor specificity. To determine if the accuracy of this sign could be improved by comparing the appearances on radiographs obtained at different times, the authors reviewed previous and current chest radiographs in 18 patients with enlarged (≥ 15 mm) and 36 patients with normal-sized subcarinal nodes. A previously seen EWRB was not visualized in 14 of 18 patients with subcarinal adenopathy (sensitivity, 78%). Obscuration of a previously visualized EWRB was present in three of 36 patients with normal-sized nodes (specificity, 92%). They conclude that obscuration of a previously seen EWRB is a useful sign in the detection of subcarinal adenopathy