[Hydatidiform mole of the placenta and coexisting, living premature infant]

A pregnancy with a partial or complete hydatidiform mole and a coexistent living fetus is a rare condition. Most cases are consistent with a twin pregnancy, with distinct borders between placenta and mole on sonography. We report a case with a single placenta with cystic structures resembling histologically a complete hydatidiform mole. The pregnancy resulted in a diploid female fetus in the 34th week of gestation with marked hypotrophy. The non-molar part of the placenta showed a complex alteration of villous maturity resulting in intrauterine growth retardation but a living fetus. No malignancy occurred post partum. The clinical and pathogenetic aspects of this rare entity are discussed.