Placental mesenchymal dysplasia and fetal hematologic disorder.

Placental mesenchymal dysplasia (PMD) is a rare, recently recognized placental vascular anomaly. About 20% of patients with this placental anomaly have Beckwith-Wiedemann syndrome. We report a case of a phenotypically normal neonate with anemia and thrombocytopenia associated with PMD. Histologic examination of the placenta showed findings consistent with PMD, including chorangioma. The patient's hematologic abnormalities resolved during the week following birth. Normal phenotypic fetuses with PMD seem to exhibit hematologic disorders at birth in some cases, especially in the presence of chorangioma.