ObjectiveThis study aimed to determine whether immunohistochemical markers in complex atypical endometrial hyperplasia could predict the presence of a concurrent endometrial carcinoma.MethodsEndometrial biopsies of 39 patients with complex atypical hyperplasia were selected retrospectively between 1999 and 2006. Only patients who underwent a hysterectomy were included. A coexisting endometrial carcinoma was present in 25 patients (64%). Immunohistochemical analysis was performed on formalin-fixed paraffin-embedded sections of the endometrial biopsies, using antibodies for MIB-1, β-catenin, E-cadherin, p53, PTEN, CD44, HER2-neu, survivin, COX-2, tenascin, and bcl-2. To evaluate the potential utility of these markers, a prediction model was constructed.ResultsIn the univariate analysis, expressions of both PTEN and HER2-neu were significantly different between the groups with and without a coexisting endometrial carcinoma (P< 0.05). Loss of PTEN staining was found in 13 (54%) and 1 (7%) of the patients with and without a coexistent carcinoma, respectively (odds ratio, 16.55; 95% confidence interval [CI], 1.87–146.65). HER2-neu expression was found in only 2 (8.6%) and 6 (43%) patients with and without a coexistent carcinoma, respectively, and was excluded from further analysis because of its low expression. A prediction model containing PTEN expression only showed an area under the curve of 73.4% (95% CI, 57.3%–89.6%). After adding MIB-1 and p53, discriminative power improved to 87.2% (95% CI, 75.1%–99.3%).ConclusionsThis study showed that PTEN expression in complex endometrial hyperplasia is a promising factor for the prediction of the presence of a coexisting endometrial carcinoma, and prediction may even better when MIB-1 and p53 expressions are considered simultaneously.