Focal nodular hyperplasia of the liver: A patient with two concurrent lesions that manifested different behavior on radiographic imaging tests

Focal nodular hyperplasia (FNH) of the liver is a relatively uncommon pathology, with only 68 cases having been documented to date in Japan. Here, we describe an interesting case; the patient had two concurrent lesions of FNH in segments three (S3) and five (S5), respectively. The two lesions differed from each other in their behavior on various radiographic imagings, i.e., computed tomography, magnetic resonance imaging, and hepatic angiography, leading to a misdiagnosis of hepatocellular carcinoma for the S3 lesion. The patient underwent left lateral hepatic resection, along with excision of the S5 lesion. Histological examination confirmed that these two lesions were FNH. Retrospective assessment of the correlation between the radiographic imagings and the morphological architecture suggested that the architectural differences between the two lesions (i.e., that, in the S3 lesion, the central scar was more developed than in the S5 lesion and was more prominent in the periphery than in the central area of the lesion) had contributed to the misdiagnosis.