1Division of Laboratory and Transfusion Medicine, Hokkaido University Hospital, 2Diagnostic Center for Sonography, Hokkaido University Hospital, 3Department of Diagnostic and Interventional Radiology, Hokkaido University Hospital, 4Department of Gastroenterology, Hokkaido University Hospital, 5Department of Gastroenterological Surgery II, Hokkaido University Hospital, 6Department of Surgical Pathology, Hokkaido University Hospital
liver, inflammatory pseudotumor, contrast-enhanced ultrasonography, Sonazoid<SUP>®</SUP>, case report
=Hepatic inflammatory pseudotumor (IPT) is a rare benign disorder with non-specified image findings that depend on the inflammatory stage. Here, we report a case of hepatic IPT with contrast-enhanced ultrasonography (CEUS) findings that changed over time. The female patient in her 40s was referred to us for close examination of a new lesion appearing in hepatic segment 5 on contrast-enhanced computed tomography (CT) during follow-up for a solitary necrotic nodule in hepatic segment 6. Ultrasonography revealed a 13-mm hypoechoic solid lesion with an ill-defined border in her liver. At the first visit, the new hepatic nodule showed a strong homogeneous enhancement pattern in the arterial phase of CEUS, while it showed a prolonged enhancement pattern in the portal phase of CEUS. In the post-vascular phase, the nodule showed an enhancement defect. Six months after these initial findings, the contrast enhancement pattern in the portal phase had changed into a washout pattern. The nodule showed a washout pattern in both the portal and equilibrium phases of contrast-enhanced CT. As dedifferentiation of hepatocellular carcinoma was not ruled out, laparoscopic partial hepatectomy was performed. The resected specimen clearly showed a distinct tumor without a capsule. Pathological findings showed an increased number of spindle cells and small blood vessels with infiltration of inflammatory cells including plasma cells in the tumor. The nodule was diagnosed as IPT. This case suggested that follow-up with CEUS might be useful to diagnose IPTs for hypoechoic solid lesions with ill-defined borders.