Endometrial intraepithelial neoplasia is associated with polyps and frequently has metaplastic change

Abstract

Aims-Endometrial Intraepithelial Neoplasia (EIN) is a monoclonal precursor to endometrioid endometrial adenocarcinoma characterized by a geographic cluster of crowded glands with epithelial cytology altered relative to the background. They may demonstrate epithelial metaplastic changes, or arise within polyps, but the frequencies of these features as encountered in practice is unknown.Methods and Results-We here report the epithelial differentiation state and polyp context of 83 sequential EIN lesions diagnosed over a 2-year period. EIN is a rare lesion, seen in only 1.4% of endometrial biopsies in a busy hospital based practice. 39 of 83 EIN cases contained metaplastic changes (18% squamous morular, 14% tubal secretory, and 5% each of secretory, mucinous or ciliated change). Endometrial polyps were more likely (OR 5.2, p<0.001) to occur in the endometrial biopsies of women with EIN lesions (43.3%), compared to the background polyp rate (12.9%) of comparable specimens from the same patient population.Conclusions-Non-endometrioid differentiation and occurrence within polyps are frequent presentations of EIN lesions. Possible mechanisms of polyp association with EIN include: nonshedding of polyp tissue creating a shelter for persistence of pre-existing neoplastic glands, or promotion of expansion of premalignant glandular clones by unique polyp stroma.

Frequent KRAS mutation in complex mucinous epithelial lesions of the endometrium

“…They commonly coexist in the same biopsy specimen 3,8 and frequently are associated with pathologic conditions including polyps, endometritis, hyperplasia and adenocarcinoma. [1][2][3][16][17][18] Mucinous change represents approximately 24% of endometrial metaplasia and is characterized by the presence of epithelial cells that have a distinctive watery blue appearance (endocervical-type epithelium) as a result of cytoplasmic accumulation of PAS-positive diastaseresistant mucin material. 1 Very rarely, mucinous changes of the endometrium exhibit intestinal-type differentiation with cellular brush border, goblet cells and neuroendocrine cells, although this is more common in the cervix where it is frequently associated with an endocervical neoplastic process.…”

Reproducibility of endometrial intraepithelial neoplasia diagnosis is good, but influenced by the diagnostic style of pathologists

“…The clue to an EIN diagnosis in these examples is the clustered and discrete nature of the altered gland focus, in contrast to randomly distributed hormonally induced metaplasias, or reactive cytological change in association with stromal breakdown. 25 An important finding of our study is that EIN morphological criteria can be easily learnt and that learning ability is not affected by years of experience. One of the reviewers in the study, who was not a gynecological pathologist and was unfamiliar with the terminology and diagnostic criteria, had a good (k 0.72) diagnostic agreement with the reference diagnoses.…”

“…8,16 It has been stressed before that when making a diagnosis of EIN within a polyp the suspicious focus should be compared with the polyp background and not that of the uninvolved endometrium, so as not to mistake the somewhat altered gland cytology that can be seen within polyps for EIN. 25 The minimum size for a lesion to be considered as EIN was determined to be 1 mm in maximum dimension within a single tissue fragment. 18,26,27 Small foci can be overlooked, also accounting for discordance in our study.…”

Which Endometrial Pathologies Need Intraoperative Frozen Sections?

“…The uterine EP has a potential risk of developing malignant tumors especially in postmenopausal women. Tamoxifen administration following breast cancer treatment may result in the development of endometrial intraepithelial neoplasia associated with an EP (Carlson, 2008). There is a risk factor for a concomitant endometrial pathology (hyperplasia, sarcoma, and carcinoma) in postmenopausal endometrial polyps.…”