The use of cytokeratin as a sensitive and reliable marker for trophoblastic tissue.

The use of human chorionic gonadotropin (hCG), human placental lactogen (hPL), and pregnancy-specific beta-1-glycoprotein (SP1) as markers for trophoblastic tissue is well documented in the literature. However, it is not widely recognized that cytokeratin is a very sensitive and reliable marker for all types of trophoblastic tissues. The authors have studied 100 cases of human placental tissue ranging in age from 2 to 40 weeks. Unlike hCG and hPL, which stain only the syncytiotrophoblast and intermediate trophoblast, cytokeratin (AE1/AE3) stains all three types of trophoblastic tissue. The staining of placental tissue for cytokeratin is strong and very consistent throughout pregnancy. Because of its high sensitivity and ability to stain cytotrophoblast, it is believed that it could be very useful in the study of the pathologic process of implantation sites, especially in tissue obtained from patients who present with missed and habitual abortions.