Endometrium, atypical hyperplasia

Atypical hyperplasia of the endometrium (also “endometrial intraepithelial neoplasia”) is a precursor for endometrial cancer. Risk factors include obesity and unopposed estrogens. It is characterized by a crowded proliferation of clonal-appearing glands. Squamous morules can also be seen.

A link to a slide of a biopsy taken after treatment with high‐dose progestins is provided in the Related Content section. Images of the ovary and endometrium at the time of hysterectomy are also provided in the Related Content section. These slides highlight the appearance of atypical hyperplasia superimposed on progestin‐treatment changes.