Non-classic presentations of hepatocellular carcinoma: two cases highlighting diagnostic pitfalls a case report

Hepatocellular carcinoma (HCC) can present as a single tumor, multiple nodules, or as diffuse hepatic involvement. On occasion, HCC extends directly into bile ducts causing tumor thrombi. Few cases of isolated intraductal HCC without parenchymal involvement have been reported. Hepatic adenomas (HA) are benign lesions with a small risk of malignant transformation, approximately 4%. Rare non-classic presentations of HCC can pose significant diagnostic challenges. We report two unusual cases of HCC. The first case involved a 73-year-old woman presenting with biliary obstruction and imaging findings suspicious for cholangiocarcinoma. Final pathology revealed a moderately differentiated HCC involving the intrahepatic bile ducts without hepatic parenchymal involvement. An extensive immunohistochemical panel was performed demonstrating positive Hepar1, glypican-3, cytoplasmic TTF-1, and CAM5.2, confirming the diagnosis. The second case involved a 39-year-old woman with an incidental large hepatic mass consistent with HA. Extensive sampling and multiple reticulin stains revealed focal reticulin loss and mild cytologic atypia, supporting a diagnosis of well-differentiated HCC arising within an HA. Awareness of these rare presentations can prevent misclassification of HCC. Intraductal tumors of the liver, require a careful gross examination and an extensive panel of immunostains, and classic imaging findings should not dictate the workup. For HA, considerations such as patient age and tumor size are important. Additionally, performing adequate sampling of the mass with liberal use of reticulin stains and careful evaluation for atypia should be part of the routine evaluation.