Histologic and Immunohistochemical Analyses of Endometrial Carcinomas: Experiences From Endometrial Biopsies in 358 Consultation Cases

Context.—Uterine serous carcinoma is biologically more aggressive than the endometrioid carcinoma. Because uterine serous carcinoma has a high propensity for lymphovascular invasion and intraperitoneal and extra-abdominal spread, accurate diagnosis of this tumor type in endometrial biopsies/curettings is critical for appropriate clinical management. Objective.—To share our experience in the evaluation of endometrial biopsy specimens in type I and type II endometrial adenocarcinoma. Design.—We retrospectively reviewed 358 biopsies containing endometrial carcinoma during a recent 3 year period of our consultation records. In cases in which our interpretation differed from the submitting diagnosis, a panel of immunostains was performed. The performance characteristics of each antibody in our panel was calculated in this group of challenging cases. Results.—Among the endometrial carcinomas we examined, a diagnosis of type I carcinoma accounted for 91% of cases (327 of 358) and type II carcinoma for 9% of cases (31 of 358); 41 cases (11.5%) were ambiguous or discordant (differing from submitted diagnoses and reviewed) based on histology alone. All 41 ambiguous and discordant cases were further evaluated with a battery of immunohistochemical markers. Of the 41 cases, 36 (88%) were ultimately classified (10 cases [24%] were endometrioid carcinoma; 18 cases [44%] were uterine serous carcinoma; 8 cases [20%] resulted in various other outcomes) and 5 cases (12%) remained indeterminate. Conclusions.—Making the distinction between type I and II endometrial carcinoma remains a common problem in general practice. Although no one biomarker provides excellent statistical performance, a panel of immunohistochemical markers is often useful in difficult cases.