Placental Mesenchymal Dysplasia without Fetal Development in a Twin Gestation: A Case Report and Review of the Spectrum of Androgenetic Biparental Mosaicism:

ABSTRACT We report a dichorionic twin gestation with diffuse placental mesenchymal dysplasia (PMD) and androgenetic biparental mosaicism (ABM) involving one twin's placenta with complete absence of fetal development for that twin. To our knowledge, this is the 1st reported case of PMD without fetal development. We discuss the gross, histologic, and genetic hallmarks of PMD and the spectrum of variability depending on degree and distribution of ABM.