Introduction/Background*Endometrial hyperplasia (EH) is characterized by an irregular proliferation of the endometrial glands with an increased gland/stroma ratio compared to the proliferative endometrium. The risk of malignancy depends on the presence of the atypia. The purpose of this study was to determine incidence of concomitant endometrial carcinoma (EC) and the risk of malignancy of the disease.

Retrospective cohort study was performed It includes a total of 120 patients diagnosed of EH by endometrial biopsy at Hospital Universitario 12 de Octubre between January 2015 to January 2020. The epidemiological and clinical characteristics of the patients were analysed. The incidence of concomitant EC was investigated in patients in whom hysterectomy was performed. Also in cases of expectant management and/or medical treatment, the rate of regression, persistence an progression of EH was studied.

Result(s)*According to the criteria of the 2014 WHO classification, 70.8% of cases were EH without atypia and 29.2% with atypia. The mean age at diagnosis was 48.9 years and 71.7% of the patients were premenopausal.. The most frequent symptom was abnormal uterine bleeding and the most ultrasound finding was pathological endometrial thickness (52.5%), followed. A suspected endometrial polyp (21.7%). Hysterectomy was performed in 25% of the total cases. In this group of patients, the incidence of concomitant EC was 33.3%, all of them in EH with atypia. In the group of patients with medical or expectant treatment, after a mean follow-up time of 25 moths, a regression of the disease was observed in 95.4% and a progression to EC in 2.3%.

Conclusion*Although EH is a benign disease entity, with a high regression-cure rate, its risk of coexistence with EC is not negligible, especially in cases where atypia is observed.