Endometrial brush cytology of advanced postmenopausal endometrium: does endometrial intraepithelial neoplasia exist in the absence of hyperplasia?

Abstract

Postmenopausal uterine bleeding is an indication to sample the endometrium for diagnostic purposes. The endometrial brush cytologies of 20 advanced postmenopausal women collected at the time of hysterectomy in order to benchmark the expected morphology of postmenopausal endometrial brushings were reviewed. No women had symptoms or gross findings of primary endomyometrial disease. Endometrium was collected at the surgical pathology laboratory using the Tao Brush and CytoRich Fixative System. After formalin fixation of the uterus, the entire endometrium was embedded for routine histology. Sixteen endometrial brushings and matched endometrial sections showed endometrial atrophy, one brushing showed many ciliated epithelial cells, and three brushings showed focal (less than 10%) epithelial-cell atypia. In two atypias, abnormal endometrial epithelial-cell sheets contained enlarged, clear nuclei with nuclear notches and grooves resembling papillary thyroid cancer. One case showed no histological counterpart to this finding. The other case showed thickening of the pericornual fundic endometrium with cystic glands. The third case with epithelial atypia showed abnormal endometrial-cell sheets with nuclei resembling atypical hyperplasia or type I endometrial adenocarcinoma; corresponding endometrial tissue sections showed rare, irregular glands and back-to-back gland clusters with equivalent nuclear features. Atypical epithelium may be found in atrophic uteri in the absence of gross endometrial thickening. This may be a common event related either to de novo intraepithelial dysplasia in a noncycling endometrium or to hyperplasia that has partly regressed with estradiol withdrawal. This study shows that, in addition to endometrial intraepithelial carcinoma (EIC), isolated atypical glands with morphological and immunohistochemical features of atypical hyperplasia or type I endometrial adenocarcinoma may be found in grossly normal advanced postmenopausal endometrium of asymptomatic patients. This atypical epithelium is readily apparent in endometrial brush preparations, but requires serial sectioning of the endometrium to be demonstrated histologically. We have not established the natural history of this lesion, and in the absence of EIC or gross endometrial thickening indicative of atypical hyperplasia, we do not know whether this degree of epithelial atypia should be an indication for hysterectomy.