Neck and thorax venous aneurysm: association with cystic hygroma.

Eight of 15 patients with mediastinal cystic hygroma were found to have abnormal enlargement of neck or thoracic veins. Five of these children had aneurysmal dilatation of the superior vena cava (SVC). Three more had mild enlargement of the SVC, which was revealed only after comparison with 20 children with no evidence of mediastinal disease. Although the association of venous aneurysms and cystic hygromas has not been previously observed, their coexistence does not appear to be coincidental: None of the patients had other causes of dilatation of the SVC. Knowledge of aneurysmal veins may be helpful to the surgeon planning resection of a cystic hygroma.