BACKGROUND: Placental mesenchymal dysplasia (PMD) is a rare placental lesion that is associated with high perinatal morbidity and mortality. Grossly, PMD is characterized by placentomegaly with thick and tortuous chorionic vessels and abnormal branching over the chorionic plate. Histologically, enlarged edematous stem villi with dysplastic vessels and cistern formation are seen among normal intermediate and terminal villi. PMD has been previously associated with Beckwith-Wiedemann syndrome, paternal uniparental disomy 6, trisomies, Klinefelter syndrome, and androgenetic-biparental whole-gene mosaicism.

CASE REPORT: We report a case of PMD in the setting of severe fetal growth restriction (FGR) (birth weight, 380 gm), with delivery at 25 weeks 1-day gestation. There was no maternal history of hypertension. The 25-week and 1-day gestation newborn infant died 20 minutes after delivery. Fetal cells obtained at amniocentesis had a 228kb deletion at 13q12.11 involving the gap junction beta-6 (GJB6) gene detected by single nucleotide polymorphism (SNP) microarray analysis. This finding was not previously reported in the setting of PMD. The histological findings of the placenta also showed some unique features that may have been associated with the specific molecular alteration that included inconspicuous cistern formation, stem villi and cell island complexes, features of shallow implantation, and a uterine pattern of chronic hypoxic placental injury.

CONCLUSIONS: A case of PMD in a 28-year-old woman with a female infant born at 25 weeks and 1-day gestation was associated with a 13q12.11 deletion in the GJB6 gene and abnormal placental histological features.

Keywords: Congenital Abnormalities, Gene Deletion, Placenta Diseases