Routine syndecan-1 immunohistochemistry aids in the diagnosis of chronic endometritis.

CONTEXT Chronic endometritis is reportedly observed in 3% to 10% of women undergoing endometrial biopsy for abnormal uterine bleeding. The diagnosis of chronic endometritis rests on the identification of the plasma cells. Their identification may be obscured by a mononuclear cell infiltrate, plasmacytoid stromal cells, abundant stromal mitoses, a pronounced predecidual reaction in late secretory endometrium, menstrual features, or secondary changes due to exogenous progesterone treatment prior to the biopsy. Syndecan-1 is a proteoglycan that is found on the cell surface of plasma cells and keratinocytes. Immunohistochemistry stains for this antibody may facilitate diagnosis of chronic endometritis. OBJECTIVE To determine whether or not routine syndecan-1 immunohistochemistry will aid in the diagnosis of chronic endometritis. DESIGN Immunohistochemistry stains for syndecan-1 were performed on 3 levels of 47 endometrial biopsies from patients with abnormal uterine bleeding. None of the patients had endometrial hyperplasia or an underlying malignancy. Clinical correlation and follow-up was attempted in 20 cases that showed evidence of plasma cells by syndecan-1 by immunohistochemistry. RESULTS Plasma cells were identified in 20 cases, 7 of which were initially diagnosed as chronic endometritis. The remaining 13 positive cases were diagnosed as tubal metaplasia (1), secretory endometrium (4), proliferative endometrium (4), menstrual endometrium (1), endometrial polyp (1), secretory endometrium with endometrial polyp (1), and endometrial polyp with exogenous hormone effect (1) based on the original hematoxylin-eosin section. CONCLUSIONS Syndecan-1 may be a useful adjunct in the diagnosis of chronic endometritis. Approximately half of the cases of chronic endometritis responded to an antibiotic regime; thus, this diagnosis is important and may potentially obviate the need for surgical intervention.