Pancreatic Origin Hepatoid Adenocarcinoma with Liver Metastasis

Hepatoid Adenocarcinoma (HAC) is a rare form of aggressive extrahepatic neoplasm with similar morphologic features to Hepatocellular Carcinoma (HCC). HAC with pancreatic origin is rare and the exact incidence is unknown. Given shared morphological and Immunohistochemical (IHC) characteristics, it may be difficult to distinguish metastatic HAC with liver involvement from primary HCC. We present a rare case of ductal type pancreatic hepatoid adenocarcinoma involving the pancreatic head, ampulla of Vater, and liver, and illustrate strategies for diagnosis and treatment. A 65-year-old woman presented with epigastric pain, vomiting, melena, and weight loss. There was direct hyperbilirubinemia with elevated hepatic markers. Imaging displayed a pancreatic head mass with moderate biliary obstruction and a hepatic lobe lesion. Fine needle biopsy of the liver mass initially was consistent with HCC, and biopsies of the pancreatic mass and ampulla walls showed pancreatic adenocarcinoma. Due to the unusual finding of co-existing HCC and pancreatic adenocarcinoma, the hepatic mass biopsy was sent for external evaluation, which revealed poorly differentiated adenocarcinoma, consistent with HAC of pancreatic origin. The tumor was positive for mucicarmine stain, HepPar1, CEA, and CK7. It was negative for MOC-31, Arginase, ALBISH, MGB, ER, TTF-1, GCDFP15, CK-20 and CDX2, thus confirming HAC. The patient was referred to outpatient chemotherapy with gemcitabine and paclitaxel however demonstrated progression and expired following recurrent bilateral pulmonary emboli. HAC may present with non-specific symptoms, is highly aggressive, and may be difficult to distinguish from primary HCC from histopathologic characteristics alone. Accurate diagnosis requires clinicohistopathologic and IHC analysis.