MUC5AC and neoplasm: On T2W MRI images, the tumor tended to be shown as an extremely high‐intensity lesion, owing to the influence of the abundant mucin in the tumor.20 This tumor has been reported to have no fibrous capsule and to directly invade the adjacent hepatic parenchyma8 and, in this study, it was found to occasionally invade the portal vein, resulting in portal vein tumor thrombus (cases 7, 15).