Placental mesenchymal dysplasia, a case of intrauterine sudden death of fetus with rupture of cirsoid periumbilical chorionic vessels.

We report a 32-year-old woman (1-gravid, 1-para) with a vesicular lesion in her uterus that was pointed out on ultrasound at 8 weeks' gestation. Amniocentesis at 15 weeks' gestation showed a normal female karyotype, 46XX. As the pregnancy advanced, the mole-like lesion became relatively reduced. Throughout gestation, the maternal human chorionic gonadotropin level was normal, but the serum alpha fetoprotein level rose as her pregnancy progressed. Her fetus did not exhibit any remarkable anomalies. The patient visited our hospital complaining of a diminished feeling of fetal movements at 36 weeks 5 days' gestation, and intrauterine fetal death (IUFD) was confirmed. She delivered a 2336-g female without any definite anomalies. A pathological examination led to a diagnosis of placental mesenchymal dysplasia, and androgenetic/biparental mosaicism in the placenta was identified using p57kip2 immunohistochemical staining. And it also revealed that the rupture of the cirsoid chorionic vessels had led to IUFD.