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Prenatal imaging and pathology of placental mesenchymal dysplasia: a report of three cases

Abstract Objective: Placental mesenchymal dysplasia (PMD) is a rare vascular anomaly characterized by mesenchymal stem villous hyperplasia. Accurate differential diagnosis of PMD is crucial to predict fetal outcomes associated with serious obstetrical complications. Methods: We reviewed the clinical and pathological features and immunohistochemical and imaging findings of three patients with PMD. Results: First trimester sonographic cystic findings identified molar pregnancy or PMD. However, PMD was highly suspected according to the maternal serum human chorionic gonadotropin (hCG) titers, fetal karyotypes, and imaging findings. The outcome of patient 1, in whom placental multicystic areas decreased as pregnancy progressed, was a live birth. In contrast, the babies of patients 2 and 3 were stillborn, and multicystic formations detected during the first trimester completely and consistently occupied the placentas. Pathological and immunohistochemical analyses using anti-CD34 and anti-D2-40 antibodies distinguished the cisternae from multiple small vessels in the villi. Immunohistochemical analyses using anti-CK7 and anti-Ki-67 antibodies did not detect excessive proliferation of trophoblasts. Most abnormal villi associated with PMD comprised stromal cells that did not react with an anti-p57kip2 antibody. Conclusion: In patients with PMD, if the percentage of the normal placental area decreases as pregnancy progresses, the possibility of fetal growth restriction and intrauterine fetal demise should always be considered. The immunostaining pattern of CD34 and D2-40 may represent a unique feature of PMD and can provide supporting evidence for the differential diagnosis of PMD.