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The expression of hormone receptors and intermediate filaments shows specific distribution patterns within EEC. MELF pattern invasion shows an altered immunophenotype compared with conventional glandular tumour areas. These findings suggest that MELF-type invasion represents a specific tumour alteration, and the reduction in hormone receptor and E-cadherin expression would be consistent with EMT. Immunohistochemical studies of EEC should consider micro anatomical variations in immunoreactivity, since these may be relevant to tumour invasion and progression.

It may be difficult to distinguish reactive glandular lesions from adenocarcinoma in situ of the uterine cervix, and although several immunohistochemical markers have established value in this diagnostic setting, none is completely reliable. We have noted that neoplastic endocervical lesions often show loss of nuclear cyclin D1 expression in contrast to benign glandular cells. Therefore, we investigated cyclin D1 staining in a series of 64 cervical biopsy specimens including examples of normal and reactive endocervical epithelium, adenocarcinoma in situ, stratified mucin-producing intraepithelial lesions, and invasive adenocarcinoma. Thirteen specimens also included a component of high-grade cervical squamous intraepithelial neoplasia. Normal endocervical epithelium usually expressed cyclin D1, although staining was typically focal, and there was increased immunoreactivity in reactive and metaplastic glandular cells including tubo-endometrioid metaplasia. In contrast, most cases of adenocarcinoma in situ were completely negative and, therefore, cyclin D1 staining distinguished benign from neoplastic epithelial cells. Although focal cyclin D1 expression was observed in 5/19 cases of adenocarcinoma in situ, the staining was associated with more marked cytological atypia precluding confusion with a reactive process. The invasive adenocarcinomas were mainly negative for cyclin D1. However, focal staining was observed in 10/19 cases and was mainly restricted to cells at the deep tumor margin, or to small infiltrative glands and detached cell clusters within the stroma. In conclusion, cyclin D1 can be included within an immunohistochemical panel to aid in the distinction between reactive cervical glandular lesions and adenocarcinoma in situ. The localized distribution of staining within invasive lesions suggests that cyclin D1 up-regulation has a specific role during the progression of some endocervical adenocarcinomas.

Endocervical adenocarcinomas that demonstrate an infiltrative growth pattern show immunophenotypic changes consistent with EMT. Frequently, these are accompanied by a morphological alteration in the tumour cells and the changes exhibit a specific micro-anatomical distribution. Epithelial-mesenchymal transition may represent an important mechanism in the progression of some endocervical neoplasms.

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