Pseudoinfiltrative tubal metaplasia of the endocervix: A potential form of in utero diethylstilbestrol exposure-related adenosis simulating minimal deviation adenocarcinoma

We report three cases of unusual tubal-type endocervical glandular proliferations simulating minimal deviation adenocarcinoma in women with a history of in utero diethylstilbestrol (DES) exposure. The lesions were characterized by haphazard glandular proliferations extending from 3.4 to 6.1 mm into the endocervical stroma and to the margins of excision in all cases. Most of the glands were small to medium-sized and round; some exhibited a moderate degree of cystic dilatation, and occasional glands had curvilinear profiles. The glandular epithelium displayed extensive tubal-type differentiation in all cases. In two cases, the glands lacked cytologic atypia and mitotic activity, and in one case, there was mild to moderate nuclear atypia with occasional mitotic activity. Immunohistochemical studies showed diffuse expression of estrogen and progesterone receptors and essentially no expression of p16 in two cases tested; there was no expression of CD10 in one case that was tested. The Ki-67 proliferation index was zero in one case and 25% in another. Human papillomavirus DNA was not detected by in situ hybridization in one case that was tested. The proliferations lacked features of mucinous and tubo-endometrioid types of minimal deviation adenocarcinoma. The clinicopathologic findings suggest the lesions are benign, and the association with in utero DES exposure raises the possibility that these could be a form of DBS-related adenosis.