Background: Chronic endometritis has been observed in 3–10% of women with irregular uterine bleeding who undergo endometrial biopsy. The diagnosis of chronic endometritis rests on the recognition of plasma cells in endometrial tissue that may show a prominent spindle cell stromal component, and is frequently difficult to date. Syndecan-1 is a cell-surface proteoglycan that is expressed on the cell surface of plasma cells. Design: Eighteen endometrial curettage cases with the diagnosis of chronic endometritis and 25 endometrial curettage cases of dysfunctional uterine bleeding, in females under the age of thirty-five in whom no other histopathologic changes were noted, were reviewed for the presence of plasma cells. Sections were then stained with syndecan-1. Results: All of the chronic endometritis cases showed easily visible syndecan-1 staining of plasma cell membranes. None of the cases of dysfunctional uterine bleeding showed presence of plasma cells in either the hematoxylin and eosin stained or syndecan-1 stained sections. Conclusions: In cases of suspected chronic endometritis in which no plasma cells can be found on hematoxylin and eosin stained slides, syndecan-1 may be an effective adjunct in the identification of plasma cells and thus aid in the diagnosis of chronic endometritis.
