Tumours of the trophoblast, [s8]common in some areas

One of the most important advances in chemotherapy was the discovery that many cases of choriocarcinoma can be cured with methotrexate. If you cannot refer a patient, you may have to treat her yourself.

In a normal pregnancy some trophoblastic cells are carried to the lungs, but do not grow there. They are only malignant when they grow outside the uterus, or abnormally within it. Here is a convenient simplification of what happens:

(1) A hydatidiform mole is a benign neoplasm of the trophoblast, in which the chorionic villi overgrow to form fluid-filled, grape-like vesicles, up to 1 cm in diameter. A mole can be complete without an embryo (more common), or partial (less common), when some fetal tissues are present (most often blood vessels containing nucleated red cells). Moles of either kind can present as an abortion, or an ectopic pregnancy. In a binovular twin pregnancy, one twin may be normal and the other a mole. Moles vary widely in incidence from 1:120 to 1:2000 pregnancies, and are more common in Asia than they are elsewhere.

(2) A non-metastasizing trophoblastic neoplasm (invasive mole) is a tumour-like process which invades the myometrium and arises from a hydatidiform mole, more commonly from a complete one. These lesions occasionally regress spontaneously.

(3) A metastasizing trophoblastic neoplasm (choriocarcinoma) arises from the trophoblast after a live birth, a stillbirth, an abortion, an ectopic pregnancy, or a hydatidiform mole.

50% of trophoblastic neoplasms develop as complications of hydatidiform moles. 25% follow full-term deliveries, and 25% follow spontaneous abortions when they present as heavy irregular bleeding. Occasionally, they follow an ectopic pregnancy.