RESUMO
A 70-year-old woman has been followed up for chronic hepatitis C and hepatocellular carcinoma which had been successfully controlled by several sessions of radiofrequency ablation. A small cystic lesion in segment IV associated with adjacent intrahepatic duct dilatation was firstly noted 4 years before on MR imaging, which showed gradual increase in size and significant interval change in the MRI signal intensity of the cystic content on the follow-up examinations. The mass finally reached 4 cm in its largest dimension, associated with slightly enhancing thickened wall, suggesting its neoplastic nature. The mass was surgically resected and a final diagnosis of mucinous cystic neoplasm (MCN) of the liver was made. MCN is usually considered to have no communication with intrahepatic duct, but in this particular case, the communication with the biliary duct was suggested from its early stage of the lesion, which would be the cause of peculiar chronological change in MR appearance.