Endometrial hyperplasia disorder is a lesion between normal hyperplastic endometrium and simple hyperplasia. Endometrial hyperplasia disorder is a focal lesion with most of the tissue resembling that seen in normal proliferating endometrium, whereas simple hyperplasia tends to be a diffuse lesion. 1. Simple hyperplasia Previously known as mild hyperplasia or cystic hyperplasia, the number of glands increases and certain glands expand into small sacs. The epithelium lining the glands is usually monolayer or pseudostratified, with columnar cells and no heterogeneity, and the cell morphology and arrangement are similar to those of the hyperplastic endometrium. 1% of simple endometrial hyperplasia can progress to endometrial adenocarcinoma. 2.Complex hyperplasia Previously called adenomatous hyperplasia, the glands are obviously hyperplastic, crowding each other and appearing back-to-back. The glandular structure is complex and irregular. Due to the proliferation of glandular epithelial cells, it may grow in a papillary pattern into the glandular cavity or sprouting into the interstitium without cellular heterogeneity. The interstitial stroma is significantly reduced. About 3% can develop into adenocarcinoma. 3.Atypical hyperplasia On the basis of complex hyperplasia, it is accompanied by epithelial cell heterogeneity, disordered cell polarity, increased volume, increased nucleoplasm ratio, dense nuclear chromatin, striking nucleoli, and more or less nuclear fission images. Severe atypical hyperplasia is sometimes difficult to distinguish from endometrial carcinoma, but if there is interstitial infiltration, it is classified as carcinoma and often requires a thorough examination after hysterectomy to confirm the diagnosis. 1/3 of patients may develop adenocarcinoma.