Aberrant Cdx2 expression in endometrial lesions with squamous differentiation: important role of Cdx2 in squamous morula formation.

Summary Only a few reports have described Cdx2 expression in endometrial lesions of the uterus. Our aim was to determine whether Cdx2 expression is related to squamous differentiation in endometrial lesions. Furthermore, we examined whether there is any correlation between Cdx2 and β-catenin, a well-known marker of aberrant nuclear accumulation in endometrial squamous foci secondary to mutation. We performed immunohistochemical analysis of 225 cases (29 normal endometrium, 28 nonproliferative conditions, 21 polyps, 46 hyperplasias, and 101 endometrioid carcinomas) that included 72 cases (4 polyps, 16 hyperplasias, and 52 carcinomas) showing morular or keratinizing squamous differentiation (SD + ). Normal endometrium and nonproliferative conditions showed no staining for Cdx2. Whereas there was a low rate of Cdx2 positivity in SD − polyps (5.9%) and hyperplasias (10%), all SD + lesions expressed Cdx2 ( P + carcinomas were positive for Cdx2, whereas only 6 SD − cases (14.0%) were positive ( P P