Rare Case of Undifferentiated Embryonal Sarcoma of the Liver that Contained an Adenocarcinoma Component

Undifferentiated embryonal sarcoma (UES) of the liver (UESL) is a tumor that is rare in adults. UESL is composed of undifferentiated mesenchymal tumor cells, with characteristic normal bile duct cells found at the tumor periphery. We present a rare case of UESL containing an adenocarcinoma component in one part of the tumor.

A 68-year-old male had a tumor with an 8-cm diameter in the left lateral liver segment. CT showed a cystic tumor with a solid component and a heterogeneous area. In the solid component, the contrast effect was weak in the arterial phase and uniform in the late phase. Imaging suggested that the internal tumor area was necrotic or hemorrhagic. We diagnosed it as hemorrhagic hepatocellular carcinoma or combined hepatocellular-cholangiocellular carcinoma. The patient exhibited normal liver function. Left lateral segmentectomy was performed. Macroscopically, the tumor was cystic, with hemorrhagic/necrotic deposits and a solid portion composed of tumor cells. Histopathologically, the tumor had 2 components. One was a nonepithelial tumor comprising immature spindle-shaped and stellate plaques, with positivity for the mesenchymal markers vimentin and CD68 and negativity for myogenic, neurogenic, and other markers. This component was diagnosed as UES. The other component comprised epithelial and adenocarcinoma tissues with differentiated bile duct cells. The tumor was mainly composed of UES cells, with the adenocarcinoma component located predominantly in the periphery.

We present a unique case of UESL containing UES cells and adenocarcinoma cells at the periphery. A combination of UESL and adenocarcinoma is extremely rare, even among hepatic carcinosarcomas.