Chorionic carcinoma is malignant, or cancerous, disease of placental tissue (the placental cells are chorionic cells, and carcinoma means a cancer). It is a rare disorder which can develop from tissue which originally produced a hydatidiform mole (described in this section) or following a normal pregnancy or miscarriage (even many years later). Since there is lots of placental tissue, there's lots of the hormone it produces - human chronic gonadotrophin - which causes the symptoms of pregnancy, and may be associated with vaginal bleeding. It invades the wall of the uterus (and is therefore sometimes described as invasive mole) after which it may be spread throughout the body. This is a disorder which is eminently treatable using chemotherapy.