Eosinophilic cell change of the endometrium: a possible relationship to mucinous differentiation

Abstract

Eosinophilic cell change is one of the most common endometrial metaplasias occurring in both non-neoplastic and neoplastic endometrium. Its phenotypic characteristics have not still been fully clarified. We examined expression of mucin core proteins in a total of 95 distinct histological areas of endometrial specimens comprising 39 benign nonhyperplastic endometria, 14 endometrial hyperplasias, and 42 endometrial carcinomas. Eosinophilic cell change was very common, seen in 27 endometrial areas (28%); mucinous metaplasia (28%) and ciliated (tubal) change (31%), were also frequently seen. Eosinophilic cell change was more frequently seen in endometrial hyperplasia and carcinoma than in benign nonhyperplastic endometrium. In endometrial carcinomas, eosinophilic cell change was frequently associated with mucinous metaplasia and the two types of metaplastic cells were occasionally intermingled in a single neoplastic gland. A total of 23 (85%) of 27 eosinophilic cell changes and 18 (72%) of 25 mucinous metaplasias showed MUC5AC expression. These frequencies of MUC5AC expression did not differ significantly among benign non-hyperplastic endometrium, endometrial hyperplasia and endometrial carcinoma. Totally, 15 (52%) of 29 ciliated (tubal) changes and two (100%) of two surface syncytial changes, which showed cytoplasmic eosinophilia at least focally, also expressed MUC5AC. Most of the endometrial changes characterized by cytoplasmic eosinophilia may be subtypes of immature mucinous metaplasia which express a mucin core protein but are not fully glycosylated.

Microarray Analysis of Gene Expression in the Uterine Endometrium during the Implantation Period in Pigs

“…MUC5AC is a secreted, large, gel-forming type of mucin (Gendler and Spicer, 1995). Its expression has been measured in human uterine endocervical epithelial cells as a major form of gel-forming mucin in the menstrual cycle (Gipson et al, 1997), and it is associated with a change in eosinophilic cells in endometrial carcinomas (Moritani et al, 2005). Decreased expression of MUC5AC in pregnant uterine endometrium suggests that MUC5AC, in addition to MUC1, may block adhesion of the conceptus trophectoderm and must be removed for the trophectoderm to undergo epithelial cell attachment.…”

Endometrial metaplasias and reactive changes: a spectrum of altered differentiation

“…Endometrial CTM is mostly described in conjunction with unopposed oestrogen levels,1 17 26–29 and its association with simple and complex endometrial hyperplasias9 and well-differentiated adenocarcinomas is striking 17–19 29. Residual CTMs can be found in atrophic endometria, where they remain unchanged even after radiotherapy.…”

“…It shares common histochemical and immunophenotypical properties with benign endocervical epithelium, such as expression of various mucin core proteins 29 47…”

“…The nature of these eosinophilic cells is poorly understood, being considered by some as a form of immature mucinous metaplasia,29 94 while for others, they represent a surface degenerative change 85. This is supported by their presence in the vicinity of endometrial granulomatous lesions 56 95…”

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

“…A general association 19 between altered endometrial glandular differentiation and endometrioid endometrial carcinoma is well documented, including squamous morular, 20 mucinous, 21 tubal 22 and eosinophilic 23 subtypes. All of these patterns have also been seen in various categories of hyperplastic endometrium, 24 but at varying rates in different patient populations 25 .…”