Placental mesenchymal dysplasia: case report with gross and histological findings
were tortuous and cirsoid (with aneurysmal dilatation). Their cut surface showed extensive thrombosis in the lumen and increased thickness of the walls. The cut surfaces of the placenta showed an admixture of normal-looking areas and numerous clusters of grape-like fluid-filled vesicles measuring up to 2.0 cm in diameter and noodle-shaped villi (Figures 1-2). Both subamniotic and intraplacental hematoma were seen.
HISTOLOGIC FINDINGS Microscopic examination revealed an admixture of normal terminal and stem villi and enlarged cystic villi. These villi were characterized by a loose, edematous, and myxoid stroma with fewer and smaller vessels than their normal counterparts; they were sometimes absent, and their location was peripheral in the villous structure. The stroma cells were mostly spindle-like or stellate in shape (Figures 3-6).
Figure 1. A – The cut surface of the placenta showing varicose chorionic vessels on the top. Myxoid areas on the cut surface of stem villi are visible B – A normal area of villi (arrow head) interfacing with noodle-like enlarged villi (arrow). A varicose chorionic vessel with obstructive thrombosis is seen on the right. 52
There were no proliferations or inclusions on the lining trophoblast. These enlarged villi were accompanied by multifocal groups of immature enlarged villi, with 10 or more vessels, that is, chorangiosis (Figure 5A). Another lesion found was multifocal diffuse chorangiomatosis (Figure 6A) with numerous enlarged villi showing a proliferation of vascular channels. The grossly visible thrombosis on dilated vessels at the chorionic plate showed an occlusive pattern (Figure 7). The umbilical artery showed mural thrombosis. There were also groups of avascular terminal villi and hemorrhagic endovasculitis.
DISCUSSION PMD is a rare disorder that was first described by Moscoso and colleagues in 1991.8 It is found in approximately 0.02% of pregnancies,1,9 with 110 cases described so far. There is a female preponderance, with female:male ratio of 3.6-4:1.4,9,10 This condition has been associated with Beckwith-Wiedmann syndrome (BWS) but it is also related to phenotypically normal fetuses,2,4 and is compatible with fetal life.1,11 BWS is characterized by omphalocele, macroglossia, macrosomia, visceromegaly, hemihypertrophy, and histologic adrenal cytomegaly,2,11 however none of these lesions were apparent at birth in this case. Cases without BWS present a high rate of IUGR4,9, (50%), and 40% result in fetal demise or neonatal death. In our case the birth weight was in the lower limit of normality (10-50 percentiles).5
Figure 2. Another area showing typical PMD findings. Dilated chorionic vessels presenting with thrombosis, and a cut surface area of the placenta showing normal areas adjacent to areas with cystic myxoid appearance. Autopsy and Case Reports 2014; 4(4): 51-56