Diagnosis of chronic endometritis in biopsies with stromal breakdown

SummaryPlasma cells are the hallmark of chronic endometritis but are not specific for upper tract infection. Plasma cells have also been noted in hormonally mediated endometrial disorders in association with gland architectural changes (“disordered proliferative” and “anovulatory” patterns), and stromal breakdown. We reviewed benign endometrial biopsies diagnosed at Beth Israel Deaconess Medical Center over a 2-year period described as disordered/anovulatory patterns ± stromal breakdown. Cases were excluded if tissue was not available; women were younger than 50 years where most diagnoses were atrophic or cancer; or diagnoses were secretory, menstrual endometrium, or polyps. The remaining 61 cases were compared to 33 samples of unremarkable proliferative endometrium. Plasma cells were quantified on hematoxylin and eosin–stained sections and using a histochemical stain methyl green pyronin. The indication for biopsy was an abnormal pattern of bleeding in 34 cases, infertility workup in 7, incidental part of workup for pain, or other findings in 5. The majority of disordered proliferative endometrium had plasma cells (61% grade 1, 17% grade 2) all seen on methyl green pyronin staining only. Two thirds of proliferative endometrium with breakdown showed plasma cells (19% grade 1, 39% grade 2, 10 % grade 3). Plasma cells were rare in inactive endometrium and noted in only 18% of unremarkable proliferative endometrium, all grade 1. Plasma cells are commonly present in the endometrium of women with dysfunctional uterine bleeding and focal stromal breakdown. Given the lack of clinical evidence for infection, the inflammation likely represents a physiologic process.