Choriocarcinoma in a term placenta: pathologic diagnosis of tumor in an asymptomatic patient with metastatic disease.

A clinically unsuspected choriocarcinoma arose in a term placenta. The patient was hospitalized for 3 weeks antepartum with preterm labor. She was delivered of a normal female infant at 36 weeks' gestation. Mother and infant were discharged after 3 days. The placenta, 465 g, contained multiple white nodules, a single infarct, and retroplacental hemorrhage. By microscopy, there was multifocal choriocarcinoma. No villous stromal invasion was found. The patient was readmitted 6 days postpartum with a serum beta human chorionic gonadotropin (hCG) value of 741,640 mIU/ml and lung metastases. She received 9 courses of multiagent chemotherapy and is currently free of tumor 1 year after diagnosis. The infant, 46,XX, remained clinically free of tumor although she had a serum beta hCG of 37 mIU/ml at 1 week of life. This placenta provides evidence of choriocarcinoma developing directly from mature placental villi in a chromosomally normal gestation and depicts a situation wherein choriocarcinoma is diagnosed correctly in the presence of villous tissue. It also demonstrates the utility of placental examination in clinically abnormal gestations.