Cholangiocarcinoma associated with multiple bile-duct hamartomas of the liver.

The case of a 61-year-old woman with a surgically resected solitary cholangiocarcinoma of the liver is reported, where many discrete multiple bile duct hamartoma (MBDH) were also seen. The latter is a congenital lesion of the liver that potentially may be confused with widespread metastatic disease. The relationship between cholangiocarcinoma and MBDH was studied histologically by the use of an immunoperoxidase technique for cytokeratin. MBDH was strongly positive for cytokeratin, while the neoplasm showed this to a lesser extent, but a clear continuity between the MBDH epithelial cells and those of the neoplasm was demonstrated by the use of this technic. The potential use for the various cytokeratins in the differentiation of primary from secondary liver tumors, is discussed. This differentiation is a significant problem to the pathologist. Although cholangiocarcinoma may, on occasion, be associated with various congenital lesions of the bile ducts, the association with MBDH is extremely rare, this being only the third reported case.