Aberrant expression of alpha-fetoprotein in intrahepatic cholangiocarcinoma: an exceptional occurrence.

A high level of serum alpha-fetoprotein (AFP) is typically indicative of hepatocellular carcinoma in patients with liver lesions. In this article, we describe an exceptional case of intrahepatic cholangiocarcinoma that occurred in a 36-year-old man with a markedly elevated serum AFP level (12310.7 ng/mL). Histopathologic examination of surgically resected liver mass showed classic morphologic features of cholangiocarcinoma, with no hepatocellular carcinoma component identified. Immunohistochemically, the tumor cells were strongly and diffusely positive for AFP, CA19-9, and cytokeratin 19 and were negative for hepatocyte antigen. The patient's serum AFP level declined to 46.2 ng/mL 1 month after surgery. To the best of our knowledge, this is the first documented case of AFP-producing intrahepatic cholangiocarcinoma with immunohistochemical evidence confirming the tumor cells to be the source of high-level AFP production.