Hepatic adenocarcinoma expressing inhibin in a young patient on oral contraceptives

A case of primary hepatic carcinoma is reported, which occurred in a 24-year-old woman with a 10-year history of oral contraceptive use, and demonstrated unique morphologic and immunohistochemical features. The tumor was located in the left hepatic lobe, measured 14 cm at its widest, and showed histologic heterogeneity. The neoplastic cells were mostly arranged in trabecular and pseudoglandular growth patterns simulating hepatocellular carcinoma; however, in focal areas, small cystic, organoid and tubular patterns predominated. Immunohistochemical stains showed a phenotype consistent with biliary differentiation (positive staining for cytokeratin 7, cytokeratin 19, carcinoembryonic antigen and CA 19-9 antigen). The tumor cells were negative for markers that would be suggestive of hepatocytic or neuroendocrine differentiation. Interestingly, they were positive for inhibin, a protein that is known to be expressed in sex cord–stromal tumors of the ovary, trophoblastic neoplasms and adrenal cortical tumors, but not in hepatic tumors. However, no definite evidence of gonadal stromal, trophoblastic, or adrenocortical differentiation was identified on extensive immunohistochemical work-up. In conclusion, this unique case may represent a rare variant of cholangiocarcinoma expressing inhibin.