Partial hydatidiform mole coexists with a living fetus: a case report

Hydatidiform mole is a benign gestational trophoblastic disease (GTD) that is classified into two types: complete and partial. Partial molar pregnancy is usually presented as a missed or incomplete miscarriage in the first trimester of pregnancy. A partial molar pregnancy coexisting with living molar pregnancy fetus is a rare occurrence.

A dead fetus and placenta product of normal vaginal delivery arrived at our hospital. This dead fetus belonged to the first pregnancy of a 21-year-old Persian woman, without gross anomaly, male gender, and was compatible with 5-6 lunar months of pregnancy. The placenta was intact with many grape-like vesicular cystic structures. Microscopic evaluation of the placenta showed large hydropic villi with cistern formation and peripheral trophoblastic proliferation mixed with normal and small-sized villi that were compatible with partial molar pregnancy.

Partial molar pregnancy has a triploid karyotype. The diagnosis and follow-up of patients with molar pregnancy are important because it has been reported that the molar pregnancy can become an invasive mole or choriocarcinoma. Many pregnancies cannot continue. If the molar pregnancy continues, its management is challenging. The coexistence of a molar pregnancy with a live fetus is a rare condition, and it increases the risk of neonatal morbidity and mortality. To achieve good outcomes, close follow-up of both the mother and fetus is advised; however, the optimal approach remains unknown.