Case report of a focal nodular hyperplasia-like nodule present in cirrhotic liver.

An 81-year-old female was referred to Sapporo Medical University Hospital because of a nodular lesion 20 mm in diameter found in the liver S8 during follow-up for type C liver cirrhosis. Abdominal ultrasonography showed a capsule-like structure, and contrast computed tomography revealed hypervascularity at the early phase and inner pooling of the contrast medium with ring enhancement at the late phase. Magnetic resonance T2-weighted imaging (T2WI) demonstrated a hyperintensity nodule with further hyperintensity signals in some parts of the nodule, and the signal pattern differed from that of typical fibrosis. SPIO-magnetic resonance imaging showed partial hypointensity signals by T2WI, which indicated the presence of Kupffer cells. Angiography did not show a spoke-wheel pattern. The results by imaging modalities indicated that the nodule was atypical for hepatocellular carcinoma (HCC) and focal nodular hyperplasia (FNH), and liver nodule biopsy was performed for histological diagnosis. Compared with the background liver, the nodule revealed high cellular density, cellular dysplasia at the periphery, a pseudo-crypt structure and irregular hepatic cord arrangement in some parts of the nodule. Among them, there was immature fibrous tissue containing arterioles with muscular hypertrophy. There has been no report of well-differentiated HCC with a central scar, and this case was presumed to be an FNH-like nodule with dysplasia physically associated with cirrhotic tissue.