Partial molar pregnancy with a chromosomically and phenotypically normal embryo: presentation of an extremely rare case and review of literature.

We present an extremely rare case of partial molar pregnancy with a chromosomically and phenotypically normal embryo and review of the literature. A 31-year-old nulliparous was referred to us at 30 weeks of gestation due to absence of fetal movements and subsequent ultrasound examination revealed intrauterine demise. Prenatal amniocentesis due to raised maternal serum α-fetoprotein had shown a karyotypically normal female embryo and second trimester ultrasound demonstrated no anatomic abnormalities. Upon induction of labor with misoprostol, a phenotypically normal embryo was delivered and the placenta showed intermixed areas of marked hydatidiform villous change and normal parenchyma. Pathologic examination of the placenta confirmed the molar change of placenta. Two are the main theories discussed herein that explain the placental molar changes in singleton pregnancies: confined placental mosaicism (one case reported to date) and placental mesenchymal dysplasia (70 cases reported). Differential diagnosis is based on histopathologic features and genetic analysis of placenta.