Relationship between eosinophils and chronic endometritis

The histopathologic diagnosis of chronic endometritis is based on the presence of plasma cells in the endometrial stroma. However, many conditions can mimic or interfere with the search for plasma cells, including the plasmacytoid stroma cells and predecidual changes of stroma cells. Eosinophils are another type of chronic inflammatory cells, which can be easily identified with routine hematoxylin and eosin stain by their characteristic eosinophilic granules. This study was conducted to investigate whether eosinophils can be used as diagnostic markers of chronic endometritis. The hematoxylin and eosin–stained glass slides of 422 consecutive endometrial biopsies were reviewed. The biopsies that have eosinophils were subjected to immunohistochemical staining with CD138, a marker for plasma cells. In all, 91 of 422 biopsies contained eosinophils with 72.5% (66/91) showing presence of plasma cells (positive staining with CD138). Of these 66 cases, only 4 cases were previously diagnosed as chronic endometritis. These results suggest the presence of eosinophils in endometrial biopsy specimen indicates a need to search for plasma cells (with immunohistochemical stain if needed) for the diagnosis of chronic endometritis.