Segmental villous mineralization: A placental feature of fetal vascular malperfusion

This retrospective analysis was performed to find out if clusters of mineralized chorionic villi can be regarded as an independent feature of fetal vascular malperfusion (FVM).

Of all 1698 placentas reviewed by the author during the last 10 years, 39 (2.3%) showed clusters of mineralized chorionic villi (Group 1), 100 cases (5.9%) showed randomly scattered mineralized chorionic villi with without clustering (Group 2), and the remaining 1559 placentas showed no villous mineralization (comparative Group 3). In doubtful cases, histochemistry stains were performed to determine the pattern of villous mineralization. Twenty three independent clinical and 43 placental variables were statistically compared among the groups: descriptive statistics (Chi-square, Fisher test or signed rank test), and logistics regression model.

Clinically, Group 1 featured shorter gestational age than Group 2, and in addition to shorter gestational age, more common oligohydramnios, polyhydramnios, induction of labor, macerated stillbirth and fetal growth restriction than Group 3. Of placental variables, fetal vascular ectasia, and clusters of avascular chorionic villi were more common in Group 1 than in Group 2, and in addition, segmental villous stromal vascular karyorrhexis was more common than in Group 3. By the logistics regression mode, segmental villous mineralization was independently associated with other histological features of FVM as a group and particularly with clusters of sclerotic chorionic villi.

FVM is characterized by temporal heterogeneity, i.e. coexistence of lesions of various duration, and strongly and independently correlates with clusters of mineralized chorionic villi. Therefore, segmental villous mineralization should be included into the category of segmental FVM. It can be seen even in totally fibrotic placentas of prolonged stillbirth when other histological features of segmental vascular malperfusion can be obscured by global villous sclerosis.