Twin pregnancy of a hydatidiform mole with a coexistent live fetus is very rare, and complete molar pregnancy is involved in most cases. A partial molar pregnancy almost always ends in miscarriage due to a triploid fetus. Here, we report a case of a 32-year-old Chinese woman with ultrasound diagnosis of a partial molar pregnancy. Amniocentesis suggested mosaicism, but the fetus was morphologically normal. The woman chose to continue the pregnancy after fully understanding the risk. The infant was delivered prematurely, and the presence of a large single placenta with molar changes. The baby\'s peripheral blood chromosomes were diploid, and the pregnant woman had no serious complications. The diagnosis, management, and monitoring of this condition will remain challenging because of its rarity. Partial hydatidiform mole combined with pregnancy can result in delivering of a normal fetus and live birth under proper management.

BACKGROUND: While gestational trophoblastic disease is not rare, hydatidiform mole with a coexistent live fetus is a very rare condition occurring in 0.005 to 0.01% of all pregnancies. As a result of the rarity of this condition, diagnosis, management, and monitoring will remain challenging especially in places with limited resources and expertise. The case we report is an interesting rare case which presented with well-described complications; only a few similar cases have been described to date.
METHODS: We report a case of a 21-year-old local Sarawakian woman with partial molar pregnancy who presented with severe pre-eclampsia in which the baby was morphologically normal, delivered prematurely, and there was a single large placenta showing molar changes.
CONCLUSIONS: Even though the incidence of this condition is very rare, recognizing and diagnosing it is very important for patient care and it should be considered and looked for in patients presenting with pre-eclampsia.