Cystic hygroma of the neck: association with a growing venous aneurysm.

Venous anomalies are rarely seen with cystic hygromas. We describe an unusual case of cystic hygroma of the neck associated with a saccular venous aneurysm that was increasing in size. A multi-modality examination of the neck-including CT, Doppler sonography, and MR imaging-revealed multiloculated cystic lesions bilaterally with predominance on the left side. A saccular venous aneurysm was noted within one of the sacs. Comparison with previous CT images showed that the aneurysm enlarged from 0.8 x 0.5 x 1.5 cm to 3.0 x 1.3 x 2.1 cm over 2 years. Identification of these malformations before surgery is critical.