Placental Mesenchymal Dysplasia
Also written as: PMD — Placental Mesenchymal Dysplasia
A rare placental vascular anomaly characterised by stem villous enlargement and mesenchymal hyperplasia, grossly resembling a partial hydatidiform mole but with a normal fetal karyotype.
Full Definition
Placental mesenchymal dysplasia (PMD) is a non-trophoblastic placental vascular disorder in which enlarged, hydropic stem villi with abnormal mesenchymal proliferation create grape-like vesicles visible on ultrasound and gross examination. Unlike a partial hydatidiform mole, PMD is associated with a diploid (typically 46,XX) karyotype, though androgenetic/biparental mosaicism is implicated in its pathogenesis. It is associated with fetal growth restriction, fetal demise, and, in a subset of cases, hepatic mesenchymal hamartoma or Beckwith–Wiedemann syndrome. Pathologists and editors must ensure PMD is clearly distinguished from molar pregnancy in all written reports because the clinical management—particularly regarding gestational trophoblastic disease surveillance—differs fundamentally.
Usage
Usage note: Do not use 'molar change' as a synonym for PMD; the distinction from hydatidiform mole has direct implications for oncological surveillance and must be explicit in all documentation.
In Context
- "Placental mesenchymal dysplasia was confirmed by histology and karyotype, ruling out partial hydatidiform mole." — Placental pathology report
- "The clinical note had documented 'molar pregnancy,' which required editorial correction to 'placental mesenchymal dysplasia' following the pathology result." — Clinical documentation review