Beta Human Chorionic Gonadotrophin (beta hCG, CGB) is a human glycoprotein hormone expressed by placental trophoblasts that stimulate ovaries to synthesize steroids needed to maintain pregnancy. HCG is a useful marker for detecting pregnancy, as well as identifying choriocarcinomas or tumors of syncytiotrophoblasts. Serum levels of HCG are also used to stage gestational trophoblastic tumors or germ cell tumors. HCG is positive in placental trophoblasts, germ cell tumors, choriocarcinomas, granulosa cell tumors, hydatidiform mole, invasive colorectal cancer, serous effusions with reactive mesothelium, and testicular seminomas with syncytiotrophoblasts. References: Mod Pathol 2004;17:701, PMID: 15001996; Cell Physiol Biochem. 2018;45(1):237-249, PMID: 29357321