Internal jugular phlebectasia in two siblings: manometric and histopathologic studies of the pathogenesis.

Two brothers, 4 years and 6 years of age, presented with a swelling in the right side of the neck. Ultrasonography and venography confirmed a diagnosis of phlebectasia of the right internal jugular vein (IJV). In an attempt to elucidate the etiology of this rare lesion, venous pressures in both the dilated right IJV and in the left IJV were taken under general anesthesia with intratracheal intubation at the time of surgery in each patient. No significant difference in pressure elevation with increase of intrathoracic pressure by overinflating the breathing bag was observed between the right and left IJV, suggesting that there would be no mechanical obstructive process generated on exertion, in each case. Microscopic examinations of a dissected portion of the dilated IJV showed paucity of muscle layer of the vein wall in the younger patient, and absence of that in the elder. Therefore, we assume that congenital muscle defect of the right IJV wall, rather than mechanical obstruction in the lower neck or the mediastinum, might cause phlebectasia. To our knowledge, this is the first report of IJV phlebectasia in siblings.