Well-differentiated peripheral cholangiocarcinoma with an unusual clinical course.

A patient with an unresectable well-differentiated bile duct tumor who survived for 15 yr after biopsy diagnosis is presented. Histologic examination of the tumor revealed bland features of bile duct adenoma despite extensive spread within the liver. Over its subsequent course, the tumor progressively replaced the liver, achieving huge size, although there was no evidence of metastases until shortly before the patient's death. This clinical course was very unusual for either bile duct adenoma or cholangiocarcinoma, but would be more characteristic of another tumor of intrahepatic bile duct origin, the biliary cystadenoma. However, this latter diagnosis was excluded with both gross and microscopic pathologic criteria. Evidence is presented to support classification of this tumor as an unusual varient of peripheral cholangiocarcinoma which requires correlation of the clinical and pathologic findings for correst diagnosis.