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“Cervicothoracic Sign”

The cervicothoracic sign is a variation of the silhouette sign on frontal chest radiography used to determine whether a superior (para)mediastinal soft tissue mass is anterior or posterior to the trachea. A positive cervicothoracic sign occurs when a thoracic lesion contacts the neck or extends into it, thereby obliterating the upper borders of the lesion on radiographs. Because the anterior mediastinum ends at the level of the clavicles, anterior mediastinal masses will disappear as it ascends above the clavicle. Examples include cystic hygroma, left superior vena cava, right aortic arch, and thymic cyst. In contrast, a lesion posterior to the trachea can have its upper border outlined by lung above the level of the clavicles (negative cervicothoracic sign), as the posterior mediastinum ends much higher. Any lesion with a discernible upper border above that level must be located posteriorly in the chest, i.e. apical segments of upper lobes, pleura, or posterior mediastinum. Examples include posterior mediastinal masses like neurofibroma. The lateral borders of a paratracheal lesion may be visible slightly above the clavicles. Examples include thyroid goitre.