Unusual Cause of Suprasternal Swelling: Cervical Extension with Herniation of Mediastinal Thymus

A 6-y-old boy was brought with complaints of intermittent suprasternal swelling noted 5 mo back. Swelling used to appear only during valsalva maneuver (Fig. 1). Swelling was non-tender and soft with poorly defined margins. Indirect laryngoscopy did not reveal any significant abnormality. Ultrasonography of neck showed well-defined hypoechoeic structure with multiple linear hyperechoeic foci within, on left side of trachea in suprasternal region, at rest (Fig. 2a). Inferiorly, lesion was continuous with mediastinal thymus. During valsalva maneuver, there was herniation of mediastinal thymus into suprasternal region, anterior to trachea extending to both sides (Fig. 2b). Magnetic resonance imaging (MRI) confirmed extension of mediastinal thymus into suprasternal region (Fig. 2c). Since cervical extension and herniation of mediastinal thymus is not a pathological finding, patient is being followed up. Failure of thymus to descent completely into mediastinum leads to ectopic cervical thymus while incomplete descent leads to cervical extension of thymus [1]. Cervical extension of thymus is seen in upto two thirds of children [1]. In addition, cervical herniation of normal mediastinal thymus during valsalva procedure can also occur and present as intermittent suprasternal swelling. Causes of suprasternal swelling apparent only during valsalva maneuver in a child include apical lung herniation, jugular venous aneurysms and laryngocele, apart from cervical thymic herniation [2, 3]. Sonography done at rest and during valsalva maneuver shows extension of thymus into the cervical region and virtually rules out the