Are Eosinophils a Specific Marker of Chronic Endometritis?

Objective: Chronic endometritis can be associated with abnormal uterine bleeding and infertility. The “gold standard” of diagnosing chronic endometritis is the identification of plasma cells, but this can be difficult. Immunohistochemical staining using CD 138 is helpful for identifying plasma cells but adds time and expense to the diagnostic process. It has been suggested that the more easily identified eosinophils comprise a surrogate marker for plasma cells. The current authors hypothesized that eosinophils are not a specific marker of chronic endometritis. Materials and Methods: The pathology database of the University Hospital, Newark NJ, was searched for cases of chronic endometritis from January 1, 1991 to August 1, 2015. Controls were endometrial biopsies that showed proliferative endometrium or disordered proliferative endometrium. Atrophy, pregnancy, secretory endometrium, and malignancy were exclusion criteria. Slides were evaluated to confirm the prior diagnosis and to determine the presence of eosinophils. Two viewers reviewed each case. Chronic endometritis was confirmed with the presence of a single plasma cell. Results: Fifty cases and fifty controls were reviewed. The review showed that 62% of cases had eosinophils present and 38% did not, whereas in controls 38% had eosinophils and 62% did not (Fisher's exact test p = 0.03). Sensitivity, specificity, positive predictive value, and negative predictive values were all 62%. Conclusions: While eosinophils were more likely to be seen in chronic endometritis, they were frequently seen in controls as well. The presence of eosinophils is not a specific marker of chronic endometritis. In the absence of plasma cells, the presence of eosinophils may suggest the need for CD 138 staining. (J GYNECOL SURG 32:345)