Immunohistochemical comparison of uterine papillary serous and papillary endometrioid carcinoma: Clues to pathogenesis

Twenty-four predominantly papillary carcinomas of the endometrium, 10 serou s and 14 endometrioid, were compared using a variety of immunohistochemical antibodies, including p53, estrogen and progesterone receptors, carcinoemb ryonic antigen, and E-cadherin. These were selected to attempt to find clue s to explain the disparate behavior of these two tumor subtypes. We found t hat 6 of 8 (75%) serous carcinomas had a p53 reactivity score of 300, where as 90% of endometrioid tumors had a p53 reactivity score of less than 20 (p = 0.0008). Combined estrogen and progesterone hormone reactivity was posit ive in 13 (100%) of endometrioid lesions compared with 3 of 8 (50%) of sero us lesions (p = 0.0117). The significantly greater p53 expression and its s ignificantly diminished hormone receptor expression indicate that papillary serous carcinomas belong to the type II group of endometrial carcinomas th at occur in a background of atrophic endometrium. are high grade, present w ith high stage disease, and have a poor prognosis. In contrast, papillary e ndometrioid carcinomas, which belong to type I carcinomas, often arise in a background of estrogen stimulated endometrial hyperplasia. are usually wel l-differentiated, and have a good prognosis. Early p53 mutations in papilla ry serous carcinoma as well as in endometrial intraepithelial serous carcin oma may partially explain their proclivity for early intraabdominal dissemi nation. Carcinoembryonic antigen expression was similar in both groups and therefore is not useful to characterize possible differences in the cell of origin. The reactivity scores for E-cadherin were also similar in the two tumor subtypes, thus nor supporting the hypothesis that decreased cell to c ell adhesion molecules might contribute to early dissemination of serous le sions.