Inflammatory pseudotumor in the liver associated with intrahepatic bile duct stones mimicking malignancy.

We describe a 71-year-old man with an inflammatory tumor arising in segment 5 of the liver. The patient was admitted because of acute pain in the right upper quadrant of the abdomen and fever. Initial laboratory tests revealed the following: serum alkaline phosphatase concentration, 634 IU/L; serum gamma glutamic transpeptidase concentration, 1,378 IU/L; serum C-reactive protein concentration, 0.89 mg/dL; and total bilirubin concentration, 8.9 mg/dL. Abdominal ultrasonography, computed tomography (CT), and magnetic resonance imaging showed a mass, 3 cm in diameter, in segment 5 of the liver. Magnetic resonance cholangiopancreatography showed a lesion of moderate-to-high signal intensity on T2-weighted images of segment 5. Endoscopic retrograde cholangiopancreatography revealed a common bile duct stone. The intrahepatic bile ducts of segment 5 could not be visualized after the use of contrast material. Endoscopic sphincterotomy was performed to remove the common bile duct stone. Antibiotics were administered soon after stone removal, and fever gradually resolved. Positron emission tomography revealed hot spots in segment 5 of the liver. Three weeks after discharge, the patient was readmitted with an acute pain in the right upper quadrant of the abdomen. Abdominal ultrasonography, CT, and magnetic resonance imaging showed enlargement of this area. Inflammatory changes of segment 5 due to cholangitis with intrahepatic bile duct stones was diagnosed. Because malignant disease could not be completely ruled out, segment 5 of the liver was resected. Macroscopic examination of the resected specimen revealed a gray, fibrotic, solid tumor associated with intrahepatic bile duct stones. Microscopic examination of the tumor showed proliferation of spindle-shaped myofibroblastic cells in a mixed myxoedematous, dense fibrotic stroma, associated with infiltration by various acute and chronic inflammatory cells. The postoperative course was uneventful, and the patient was discharged on postoperative day 16.