Multicystic biliary hamartoma mimicking intrahepatic cholangiocarcinoma: report of a case.

Multicystic biliary hamartoma (MCBH) is a rare cystic disease of the liver. A 69-year-old man was referred to our hospital with radiographic abnormality. Physical examination of the patient was unremarkable, and he denied any previous medical, travel, or surgical history. An abdominal computed tomography (CT) scan demonstrated a 3-cm low-density lesion in segment 3 of the liver, with dilation of the intrahepatic bile duct. The peripheral site of this lesion was slightly enhanced in the arterial phase. In the portal phase, the peripheral site was enhanced more clearly and showed a honeycomb-like dilated bile duct. Ultrasonography also revealed that the lesion was an irregularly shaped mass. On magnetic resonance imaging (MRI), T1-weighted images revealed a low-density mass and T2-weighted images revealed a dappled-density mass with honeycomb-like dilated bile duct and dilation of major intrahepatic bile duct. The patient was diagnosed with intrahepatic cholangiocarcinoma (ICC) and underwent left hepatectomy. However, pathological findings revealed that the lesion was MCBH. Our case highlights the potential difficulties in differentiating between MCBH and ICC under such circumstances.