280 A Fascinating Case of Combined Hepatocellular Carcinoma-Cholangiocarcinoma (cHCC-CCA) diagnosed on Liver Core Biopsy

Introduction/Objective Combined hepatocellular-cholangiocarcinoma (cHCC-CCA) is a rare primary hepatic malignancy accounting for 2-5% of primary liver carcinomas. cHCC-CCA is defined by presence of histologic features of both hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA). In this submission, we present an interesting case of cHCC-CCA and highlight the important features and significance of correctly diagnosing cHCC-CCA. Methods/Case Report We report an interesting case of cHCC-CCA in a 66-year-old male with a 5 cm targetoid mass in hepatic segment 8, suspicious for an atypical HCC. The patient underwent an image guided liver mass biopsy. H&E slides of the core biopsy showed two distinct morphologies. The first population of tumor cells demonstrated polygonal cells with abundant eosinophilic to amphophilic cytoplasm, and prominent nucleoli. Adjacent to this population, a second population of tumor cells demonstrated poorly formed glands set within a desmoplastic stroma, cytologically showing pleomorphism and prominent nucleoli. Immunohistochemical stains of the first population were positive for glypican-3, Hep Par-1(rare cells), arginase-1 (rare cells), while being negative for CK7, and CK19. Special staining for reticulin showed a loss of staining. These immunomorphological features are suggestive of hepatocellular carcinoma. The immunoprofile for second population of the tumor showed positive for CK7 and CK19, and negative for glypican-3, Hep Par-1, and arginase. These characteristics are consistent with cholangiocarcinoma. This case was signed out as Combined hepatocellular-cholangiocarcinoma (cHCC-CCA). Results NA Conclusion CHCC-CCA requires presence of two morphologically and immunohistochemically distinct populations of HCC and CCA and there is no minimum cut-off for the amount of each component for the diagnosis of cHCC-CCA. The two components can be either close to each other or intermingled; however, collision tumors are not part of this entity. Distant metastasis of this tumor can show either cHCC-CCA features or any individual component of the combined tumor. Correct diagnosis of cHCC-CCA is of utmost importance given that cHCC-CCA has a worse prognosis and different clinical follow-up pattern than a conventional HCC. As cHCC-CCA are treated clinically as a more aggressive tumor along the lines of the CCA component so we should always keep this rare diagnosis in our mind when examining the liver neoplastic biopsies.