Histopathological examination of the ectocervical biopsy in non-transplanted uteri: A study contributing to the provisional scoring system of subclinical graft rejection after uterus transplantation

Introduction Uterus transplantation is a causal treatment for absolute uterine factor infertility. Assessing rejection signs using a histopathological examination of the ectocervical biopsy from the transplanted uterus is common practice in all human uterus transplants worldwide to date. A provisional scoring system was used for the histopathological assessment of subclinical rejection signs in uterus recipients. Here we hypothesized that histopathological and immunohistochemical findings in the normal uteri would differ from the borderline category of subclinical rejection in uterine transplants. Material and methods This prospective observational study included ectocervical biopsies of 54 women who underwent hysterectomy for benign reasons. All biopsy samples were assessed histopathologically and immunohistochemically. Results Most of the ectocervical biopsies showed clustering lymphocytic infiltrates affecting the stromal-epithelial interface with the epithelial influx of lymphocytes, primarily CD45RO-positive activated T-cells with CD8 T-lymphocyte predominance. CD4-positive T-lymphocytes and B-cells were rarely detected in the ectocervix. These morphological findings and immunoprofiles of lymphocytic populations overlapped with the so-called borderline changes defined in the provisional scoring system for rejection in the transplanted uteri. The immunoprofiles of ectocervical and endocervical lymphocytic populations differed, with strikingly prominent B-cell participation in the endocervix vs the rare detection of B-cells in the ectocervix. Conclusions The histopathological and immunohistochemical findings in the uteri of premenopausal women were similar to the borderline category of the currently used provisional scoring system of subclinical uterine rejection utilized in all uterine transplant studies. However, future similar studies are required to validate our findings.