Composite Adenocarcinoma and Choriocarcinoma of the Sigmoid Colon with Hepatic Metastasis of the Choriocarcinomatous Component

ABSTRACT

A rare case of hepatic metastasis with a choriocarcinomatous component from a composite adenocarcinoma and choriocarcinoma of the sigmoid colon in a 60-year-old man is reported. The hepatic metastasis displayed choriocarcinoma with extensive hemorrhagic necrosis. The tumor cells were poorly differentiated with scattered foci of bizzare syncytiotrophoblastic cells. Retrospective examination of the previous colonic carcinoma proved that the tumor was composed of two distinctive elements. One was a moderately well differentiated adenocarcinoma located in mucosa and submucosa. The other was a deep seated and undifferentiated carcinoma which was made up of hyperchromatic bizzare cells with syncytiotrophoblastic cells. There were transitional foci from adenocarcinoma to undifferentiated carcinoma with trophoblastic cells. Immunohistochemical staining showed beta-hCG expression in the undifferentiated cells of both the primary and the metastatic tumors. Implications for the possible origin and cause of tumor cell heterogeneity are briefly discussed.