A case of inferior right hepatic vein-right hepatic vein bypass with interrupted inferior vena cava compressed by focal nodular hyperplasia in caudate lobe.

Focal nodular hyperplasia (FNH) is a relatively common benign liver tumor with rare indications to surgery. Budd-Chiari syndrome is a rare condition caused by interrupted hepatic venous outflow in the hepatic veins and inferior vena cava (IVC). A 42-year-old woman was referred to our department with a hepatic tumor. Patient's chief complaint was leg edema. Because of this symptom, it was difficult for the patient to stand for more than 20 min in the evening. Computed tomography (CT) showed a hypervascular mass compressing IVC in the caudate lobe of the liver. Fine needle aspiration was performed, and preoperative diagnosis was focal nodular hyperplasia (FNH). Hepatic resection of the right caudate lobe was performed. Postoperative histological examination revealed that the tumor was FNH. After surgery, the patient's leg edema disappeared, and postoperative CT revealed that severe IVC stenosis was improved. Although there have been several reports of giant FNH causing Budd-Chiari syndrome, this case shows the stenosis of IVC below the root of hepatic veins causing Budd-Chiari-like syndrome without portal hypertension. The location of the tumor considerably attributed to the congestion of venous flow in IVC causing various symptoms and intrahepatic inferior right hepatic vein-right hepatic vein bypass. The surgical indication of FNH is limited in most cases; however, the current report alerts that the location of FNH should be taken into account when monitoring it.