Chronic endometritis: the role of immunohistochemistry in the detection of plasma cells.

The diagnosis of chronic endometritis depends upon the detection of plasma cells within the inflammatory infiltrate in the endometrium. To determine whether an immunohistochemical stain for plasma cells would enhance the detection of them and the diagnosis of chronic endometritis, we investigated 65 cases, including normal, proliferative, and secretory endometria, late menstrual endometria, endometrial polyps, and cases suspected of being, or diagnostic for, chronic endometritis. Twenty cases were positive by immunoperoxidase staining, 14 of which were positive by morphologic evaluation. Scattered isolated plasma cells which had been missed by histologic examination were detected by immunoperoxidase in three cases of early proliferative endometrium, and one case each of cystic glandular hyperplasia, 16-day endometrium, and late menstrual endometrium. Hence, the immunoperoxidase technique was more sensitive for detecting isolated plasma cells which were missed by standard screening techniques. In addition, the immunoperoxidase stain was useful for defining the spectrum of plasma cell morphologic characteristics within endometrium and, in retrospect, confirmed the differences between plasma cell and endometrial stromal cell morphologic features on hematoxylin and eosin sections.