Hepatoid carcinoma of the gallbladder.

Hepatoid carcinoma is a special type of extrahepatic tumor associated with hepatic differentiation, and has the morphological and functional features of hepatocellular carcinoma. Hepatoid carcinoma of the gallbladder is very rarely reported in the literature. We report a case of hepatoid carcinoma of the gallbladder in a 71-year-old female who presented with abdominal pain and was first diagnosed as cholelithiasis with cholecystitis. The microscopic findings of the gallbladder after cholecystectomy showed an area of tumor with polygonal cells, eosinophilic cytoplasm, distinct cell borders, round vesicular nuclei and prominent nucleoli, arranged in trabecular pattern resembling hepatocellular carcinoma intermingled with areas of adenocarcinoma or cholangiocarcinoma. The specimen from the pancreas also showed the same type of tumor cells. Histochemically, some of tumor cells were positive for Victoria Blue, Stein, and PAS. The immunohistochemistry for alpha-fetoprotein (AFP) showed strong intra cytoplasmic positivity, both in tumor cells with hepatic differentiation and tumor cells with bile duct epithelium differentiation. Based on these findings, this case was diagnosed as hepatoid carcinoma of the gallbladder with metastasis to the pancreas. This is the first case that has been reported in our department.