Anterior mediastinal lymphadenopathy in sarcoidosis.

Several lymph node chains in the anterior mediastinum lie between the sternum and the trachea. On a lateral chest radiograph they form two distinct groups separated by the superior vena cava. One group projects anterior to the trachea and is formed by overlapping nodes of the anterior paratracheal and the left anterior mediastinal (prearterial) chains. The other is in front of the superior vena cava, composed of the right anterior mediastinal (prevenous) and horizontal chains. The position of these chains prevents them, even when enlarged, from being seen on posteroanterior chest radiographs or tomography: frequently they may not be appreciated on lateral chest films. Therefore lateral chest tomography is the best method to evaluate anterior mediastinal lymphadenopathy. With this technique, anterior mediastinal lymphadenopathy in sarcoidosis should be found more frequently than indicated in the literature.