A Case of Inflammatory Hepatocellular Adenoma Complicated by Steatohepatitis

Abstract

A 54-year-old man with hypertension, dyslipidemia, diabetes mellitus and fatty liver was referred to our institution for accurate diagnosis of a 4-cm space-occupying lesion in subsegment 6 of the liver, identified on ultrasonography as an iso-to hypointense lesion with clear margins. Dynamic computed tomography disclosed light accumulation of contrast medium at the margins of the space-occupying lesion from the arterial phase through to the venous phase. Sonazoid-enhanced ultrasonography showed staining of the tumor margins in the vascular phase, disappearing in the post-vascular phase. Hepatic arteriography identified the space-occupying lesion as hypervascular. Since accurate diagnosis by imaging was difficult, tumor resection was performed to exclude hepatocellular carcinoma, after obtaining consent from the patient. Histological examination revealed steatohepatitis and sinusoidal dilatation, representing socalled peliosis hepatis, in the surroundings, while the tumor showed mild hepatocellular atypia. On immunohistochemistry, tumor cells were positive for liver fatty acid-binding protein, glutamine synthetase and serum amyloid A, and negative for β-catenin and glypican 3. Glutamine synthetase, in particular, showed strong diffuse staining. Inflammatory hepatocellular adenoma was thus considered the most likely diagnosis. The pathogenesis and outcome of inflammatory hepatocellular adenoma are not fully understood, and this case with concomitant steatohepatitis was considered worth reporting.