Primary follicular lymphoma of the extrahepatic bile duct mimicking a hilar cholangiocarcinoma: case report and review of the literature.

We report a case of a 53-year-old Asian woman who presented with abdominal pain, bloating, dysphagia, and signs of incomplete biliary obstruction, having elevated liver function tests but without increased bilirubin. Imaging studies revealed a mass measuring 6.0 x 8.0 cm at the porta hepatis extending to the right lobe of the liver and obstructing the common hepatic duct, causing mild to moderate intrahepatic biliary dilation and variable occlusion of the right portal vein. At laparotomy, an infiltrative neoplasm was noted at the hilum that involved the common bile duct, right and left hepatic ducts, and the right lobe of the liver. Extended right hepatectomy and resection of the extrahepatic bile duct and right portal vein was performed. Histologic examination revealed a high grade follicular lymphoma (grade 3A) with a predominantly follicular pattern of growth. Portal lymph nodes and a staging bone marrow biopsy showed no evidence of lymphoma. The patient subsequently received chemotherapy. Postoperative follow-up of more than 4 years has been uneventful, without disease recurrence. To the best of our knowledge, this is the third report of a primary extranodal follicular lymphoma of the extrahepatic biliary system.