Primary combined hepatocellular-cholangiocellular sarcoma: An unusual case.

Primary liver carcinosarcoma is rare. Here we report an unusual case of liver carcinosarcoma containing combined hepatocellular cholangiocarcinoma. A mass in the right liver lobe of a 45-year-old man was accidentally discovered by ultrasonic inspection and computed tomography (CT) scan. Surgical resection was performed following a diagnosis of primary liver cancer. Micropathologically, both carcinomatous and sarcomatous elements were present, and diagnosis of liver carcinosarcoma was confirmed. The carcinomatous element consisted of hepatocellular carcinoma and foci of cholangiocellular carcinoma. The sarcomatous element was composed of spindle cells and bizarre cells, as well as foci of osteosarcoma and chondrosarcoma. Hepatocellular carcinoma cells diffusely expressed both hepatocyte specific markers cytokeratin (CK) 8/18 and cholangiocyte specific markers CK19, and sarcoma cells were positive for vimentin. Interestingly, both carcinomatous and sarcomatous cells expressed epithelial membrane antigen. CD117-positive ductular reactions and small undifferentiated cells were observed. A liver progenitor cell origin of the liver carcinosarcoma was proposed.