Well-differentiated HCC manifesting hyperattenuation on CT during arterial portography

A rare case of well-differentiated minute hepatocellular carcinoma (HCC) with hepatitis C virus-related cirrhosis, with unusual radiologic features, is presented. A 10-mm hypoechoic nodule disclosed by ultrasound in segment six showed hypoattenuation on computed tomography hepatic arteriography and hyperattenuation on computed tomography during arterial portography, indicating that the portal vein may have been the dominant vascularity of the nodule. Contrast-enhanced ultrasound revealed hypovascularity in the early arterial phase, isovascularity in the late vascular phase, and the same perfusion as that surrounding the liver parenchyma in the post-vascular phase, with the same pattern observed on the two imaging techniques. These findings were considered not compatible with those of well-differentiated HCC. Ultrasound-guided biopsy showed histological features of well-differentiated HCC with over two-fold the cellularity of the non-tumorous area with a high nuclear/cytoplasmic ratio, increased cytoplasmic eosinophilia, slight atypia and fatty change with an irregular thin trabecular pattern. Further studies may provide insights into the correlation between tumor neovascularity in multistep hepatocarcinogenesis and dual hemodynamics, including the artery and the portal vein.