Endometrial hyperplasia

Classification

Endometrial hyperplasia begins as a physiological response to estrogen, but gland cells may undergo changes predisposing to cancer. The World Health Organization (WHO) system previously had four categories: simple hyperplasia without atypia, complex hyperplasia without atypia, simple atypical hyperplasia, and complex atypical hyperplasia.

In 2014, the WHO updated the classification, removing the simple/complex distinction and focusing solely on the presence or absence of atypia. Non-atypical hyperplasia shows irregular glands (simple) or crowded, budding glands (complex) without worrisome cell changes; about 1.6% of such patients eventually develop cancer. Atypical hyperplasia exhibits cell stratification, tufting, loss of nuclear polarity, enlarged nuclei, and increased mitotic activity, resembling cancer but without invasion; 22% of these patients later develop cancer.

Prognosis

Studies on progression risk have largely focused on atypical hyperplasia, with no estimates specifically for non-atypical cases. If untreated with hysterectomy, endometrial hyperplasia progresses to adenocarcinoma within 20 years in about 5% of cases without atypia and in 28% of cases with atypia (95% CI, 8.6% to 42.5%). Because carcinoma is already present in over 40% of patients with atypia, the 28% progression rate may be an underestimate, and the true figure may be closer to the upper end of the confidence interval.

Did You Know?

• Diagnosis is made by endometrial biopsy or curettage of the uterine cavity.
• A workup may be prompted by abnormal uterine bleeding or atypical glandular cells on a pap smear.