Hydatid cyst of the liver presenting as an inferior vena cava obstruction.

A 48-year-old woman presented with clinical features suggestive of an obstruction of the inferior vena cava (IVC). Abdominal sonography showed a 15- x 14-cm cystic mass involving the medial segment of the left hepatic lobe and the anterior segment of the right hepatic lobe. We visualized multiple intracystic floating membranes, a detached endocyst, and a daughter cyst within the main cyst. The cyst was compressing and effacing the intrahepatic portion of the IVC and the right atrium. Sonography of the right and left hepatic veins showed blood flow in the normal direction, but spectral analysis showed that the flow was continuous, possibly owing to extrinsic compression of the IVC at the site where the hepatic veins drained into the IVC. The patient responded well to percutaneous treatment of the hydatid cyst. This case represents a rare presentation of a hydatid cyst of the liver.