Hepatic inflammatory pseudotumor mimicking intrahepatic cholangiocarcinoma: report of a case.

Hepatic inflammatory pseudotumor (IPT) is a relatively rare lesion comprised of proliferating fibrovascular tissue infiltrated by inflammatory cells. IPT has a potential for recurrence and persistent local growth. We present a case of hepatic IPT mimicking a periductal-infiltrating type of intrahepatic cholangiocarcinoma (ICC) in a patient whose serum carbohydrate antigen 19-9 was slightly elevated. We performed a left hepatic lobectomy with resection of the extrahepatic bile duct and regional lymph node dissection under a preoperative diagnosis of ICC. However, histological examination of the resected tumor revealed granuloma tissue with lymphocyte infiltration, mainly by plasma cells, and proliferation into the surrounding connective tissue, and the lesion was ultimately diagnosed as hepatic IPT. This case points out the difficulties in differentiating between hepatic IPT extending along Glisson's sheath and ICC, based on imaging findings alone.