ABSTRACT
Squamous metaplasia of the membranes is a frequently seen phenomenon of no clinicopathologic significance. It is characteristically distributed on the amnion around the cord insertion site and appears as slightly elevated, gray-white plaques, which are usually only a few millimeters in diameter (Figure 86a). Since the plaques represent sites of amniotic epithelial metaplasia, and are not deposits, they cannot be easily removed from the amniotic surface by scraping. This resistance to removal and the peri-insertional distribution are helpful features in distinguishing squamous metaplasia from amnion nodosum, described below. Histologically, the plaques are seen as sites of change in the monolayer of amniotic cuboidal epithelium to a multilayered keratinizing squamous epithelium (Figure 86b). Their location and appearance are compatible with sites of reactive change, due to traction and associated displacement of the amnion from the chorion, at the cord insertion site, that likely occur with fetal movement.
