Non-atypical endometrial hyperplasia: risk factors for occult endometrial atypia and malignancy in patients managed with hysterectomy.

Objective: To determine the risk factors for occult endometrial atypia and malignancy in patients diagnosed with non-atypical endometrial hyperplasia (NEH) on endometrial biopsy.

Methods: All new cases of NEH diagnosed between April 2015 and March 2016 at KK Women's and Children's Hospital, who underwent hysterectomy as first-line treatment, were included in the study. Patients with a history of endometrial hyperplasia or malignancy were excluded from the study. Patient demographics (e.g., age, parity, body mass index [BMI]), medical history, and clinical presentation were obtained for analysis.

Results: In total, 262 patients were diagnosed with NEH, of which 18.3% (n=48) underwent hysterectomy as first-line management. The average time to surgery was 77.0±35.7 days. All cases were diagnosed by dilation and curettage, and hysteroscopy. The mean age was 51 years, and the mean BMI was 26.9±5.8 kg/m2. Histology from the hysterectomy specimen showed 9 (18.8%) patients with atypical hyperplasia and 2 (4.2%) with grade 1, stage 1A endometrioid adenocarcinoma. Patients with higher grade final pathology had significantly lower median parity (1 vs. 2, P=0.039), higher mean BMI (30.1±6.5 vs. 25.9±5.3 kg/m2, P=0.033), and BMI ≥30 kg/m2 (54.5% vs. 13.5%, P=0.008, odds ratio 7.68), compared to patients whose final histology showed NEH or no residual hyperplasia.

Conclusion: Occult endometrial atypia and malignancy were found in 18.8% and 4.2% of patients with an initial diagnosis of NEH, respectively. High BMI and low parity were identified as significant risk factors for high-grade endometrial lesions in patients with NEH.