1Department of Radiology Nihon University School of Medicine, 2Second Department of Pathology Nihon University School of Medicine
Focal nodular Hyperplasia, Ultrasonic angiography, Marginal hypoechoic zone
A clinically and histopathologically based diagnosis of focal nodular hyperplasia (FNH) of the liver was made in the case of a 36-year-old woman. Ultrasonic angiography showed a filling pattern centrifugal to the periphery during the early phase after an injection of carbon dioxide (CO2) microbubbles. Ultrasonic angiography after CO2 injection helped to confirm the diagnosis. A marginal hypoechoic zone (halo) around the lesion proved to be a significant finding in differentiating FNH from hepatocellular carcinoma. Comparison of the ultrasonographic and histopathological findings led us to presume that the halo was caused by proliferative vessels surrounding the tumor.