An aggregate of lymphocytes with a few plasma cells is seen between glands. Plasma cells tend to concentrate beneath the epithelial surface and around glands.

Irregularly-shaped glands and reactive spindled stroma are accompanying changes in chronic endometritis.

A bird's eye view of odd-shaped glands situated in spindled stroma.

Eosinophilic change is seen in this example of chronic endometritis, along the surface epithelium.

Higher power of this area shows an occasional plasma cell (see arrow). Altered glands were also apparent in many fragments.

Another case shows a lymphoid aggregate (bottom image) and a spindled stroma with vessels.

A lymphoid follicle is seen here in this same case of chronic endometritis. This finding is a useful clue to the diagnosis but by itself is not diagnostic.

Higher power of another focus in this same biopsy shows easily found plasma cells. The cells are larger and more distinct than stromal cells, which can mimic plasma cells. The spindled background and altered glands, however, are what prompt a search for chronic endometritis.

Large areas of glandular stromal breakdown (upper half) are seen in this case, which is a direct consequence of chronic endometritis, causing intermittent spotting.

Endometritis accompanies pelvic inflammatory disease of the upper genital tract. Causes include instrumentation (biospy, IUD), recent pregnancy (term or abortion) or presence of an organic lesion (polyp, leiomyoma or carcinoma). Infectious agents include Chlamydia trachomatis, Neisseria gonorrhoeae, Streptococcus agalactiae, Myocoplasma hominis and viruses such as CMV and herpesvirus.1,2

Traditionally, endometritis has been separated into acute and chronic forms. Plasma cells are necessary for the diagnosis of chronic endometritis. Unlike lymphocytes, plasma cells are not present in normal endometrium. Prominent neutrophils are seen in acute endometritis, but may be present in variable numbers in chronic endometritis.

Other than the presence of plasma cells, other key features to diagnose chronic endometritis include reactive stromal changes and glandular changes. Stromal cells become more spindled and glands become irregularly shaped with delayed secretory maturation (if the woman has ovulated).

In situations when it is difficult to detect plasma cells, a methyl green pyronin or CD138 stain can be used.2

Typically affects reproductive age women, although it may occur in postmenopausal women as well. Commonly presents as intermenstrual bleeding or chronic pelvic pain. May be associated with infertility (although some studies do not find an association).1,2

Treatment usually involves empiric antibiotic therapy with broad spectrum coverage. Underlying factors should be evaluated such as immunosuppression or poorly controlled diabetes.

The inflammation commonly responds to antibiotic therapy, however residual scarring may cause chronic symptoms.