Serous Intraepithelial Carcinoma Arising in an Endometrial Polyp: A Proposal for Modification of Terminology

Abstract

Endometrial adenocarcinoma is the most common gynecologic malignancy in the United States, most frequently presenting in postmenopausal women. Two major subtypes of endometrial adenocarcinoma are now well recognized. The more common (type 1) has an endometrioid morphology with several variants. The far more aggressive subtype (type II) that accounts for only 10% of cases more frequently displays a serous morphology, but may have pure clear cell differentiation. We present here an interesting aspect of the type II carcinoma manifested in a case we recently received for consultation at the Department of Pathology, Yale New Haven Hospital. Seven slides were available for review from a 67-year-old woman, who had undergone a total hysterectomy and bilateral salpingo-oophorectomy. An endometrial polyp (Figure 1) was the major finding. Within the polyp, a high-grade malignant serous epithelium focally replaced the surface epithelium and superficial glands of the endometrial polyp (Figure 2). Despite the absence of any myometrial invasion, endocervical mucosal involvement without stromal invasion was identified (Figure 3). The non-neoplastic endometrium was atrophic. The neoplastic cells were immunoreactive for p53 (Figure 4) and showed a high mitotic index on Ki-67 immunostain, supporting the morphologic impression. The clinical, morphologic examination, and immunohistochemical profile were classic for the so-called endometrial intraepithelial carcinoma (EIC).