Of those, at least 30% were initially diagnosed as adenocarcinoma on the basis of histology but were ultimately ruled to be choriocarcinoma on the basis of immunohistochemical profiles showing strong positivity for hCG, with mixed responses for cytokeratin 7 (CK7), caudal type homeobox-2 (CDX-2), and villin, among other stains [21, 30, 31]. The gene discussed is CDX2; the disease is choriocarcinoma.