CDKN1C and dysplasia: In our case, the negative CD-34 immunohistochemical stain in the cells that line the cistern, the normal p57 expression in the trophoblast, but absent stromal staining in placental mesenchymal dysplasia, the p53 protein expressed in the nuclei of some trophoblastic cells (p53 wild-type pattern), and the intense positive cytokeratin 7 staining of the villous trophoblastic cells, settled the diagnosis.