title: Placental mesenchymal dysplasia.
abstract: BACKGROUND
  Placental mesenchymal dysplasia is characterized by placentomegaly and may be mistaken for molar pregnancy both clinically and macroscopically because of the presence of "grapelike vesicles." It may be associated with a completely normal fetus, a fetus with growth restriction, or a fetus with features of Beckwith-Wiedemann syndrome.
  
  
  OBJECTIVE
  To review the etiology, molecular pathology, gross and microscopic features, clinical presentation, complications, and differential diagnosis of placental mesenchymal dysplasia.
  
  
  METHODS
  The PubMed and the Medline databases were systematically searched for articles between 1970 and 2006. The following keywords were used: placental mesenchymal dysplasia, mesenchymal hyperplasia, molar pregnancy, pseudomolar pregnancy, Beckwith-Wiedemann syndrome, and placentomegaly. Relevant references from review articles were also searched.
  
  
  CONCLUSIONS
  Placental mesenchymal dysplasia should be considered in the differential diagnosis when the ultrasonographic findings show a cystic placenta. Close attention should be paid to fetal morphology for early recognition of fetal complications and to prevent unnecessary termination of pregnancy in cases associated with a normal fetus.
authors.affiliation: University of Hawaii Pathology Residency Program, Honolulu, USA. zahipar@yahoo.com
authors.forename: Zahida
authors.initials: Z
authors.lastname: Parveen
authors.forename: Jane Elaine
authors.initials: JE
authors.lastname: Tongson-Ignacio
authors.forename: Cory R
authors.initials: CR
authors.lastname: Fraser
authors.forename: Jeffery L
authors.initials: JL
authors.lastname: Killeen
authors.forename: Karen S
authors.initials: KS
authors.lastname: Thompson
mesh_terms: D001506:Beckwith-Wiedemann Syndrome / Q000209:etiology; D003937:Diagnosis, Differential; D005260:Female; D005317:Fetal Growth Retardation / Q000209:etiology; D006801:Humans; D006828:Hydatidiform Mole / Q000175:diagnosis; D008648:Mesoderm / Q000473:pathology*; D010920:Placenta / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D010922:Placenta Diseases / Q000175:diagnosis / Q000209:etiology / Q000473:pathology* / Q000503:physiopathology*; D010929:Placentation / Q000502:physiology*; D011247:Pregnancy; D014463:Ultrasonography