Jugular phlebectasia.

The most common cause of a mass in the neck that appears only during straining is a laryngocele. However, the rare jugular phlebectasia may present in a similar manner. Dilatation of the internal jugular vein with a Valsalva maneuver suggests a mechanical obstruction in the neck or mediastinum, but the exact cause is still unknown. Nevertheless, dilated internal jugular veins have been excised, as in the case reported here, and found to have thinning of the wall but no associated abnormality.