A case of inferior vena cava thrombosis caused by compression due to growing giant liver cyst.

We report a case of inferior vena cava (IVC) thrombosis caused by compression by a giant liver cyst. A 68-year-old man with a 1-day history of abdominal pain was referred to another hospital. Ultrasonography (US) and enhanced computed tomography (CT) showed a multilobular cyst on the right liver lobe that had increased to 300 mm in diameter from 90 mm 18 months earlier. Thrombosis was detected in the IVC, which was compressed by the cyst. Percutaneous transhepatic cyst drainage achieved no significant change in size. Cytological analysis from the percutaneous drainage tube fluid showed no evidence of malignancy. He was referred to our hospital for further assessment and treatment. Enhanced US using perfluorobutane, CT, and magnetic resonance imaging showed no tumorous lesions in the cyst. Thus, we diagnosed it as a multilobular cyst with no evidence of malignancy. A 3-week course of heparin resulted in the successful resolution of the thrombosis. Cystectomy was subsequently performed and pathological examination showed a multifocal cyst consisting of central suppurative inflammatory exudation and hemorrhagic material, with no malignancy. This case demonstrates that giant, expanding, non-tumorous cysts can cause IVC thrombosis. Careful treatment using heparin successfully resolved the thrombosis and allowed successful cystectomy.