Differential diagnosis between normal endometrium and endometrial hyperplasia with immunostaining cytology using anti-LeY monoclonal antibody.

We have previously reported that both endometrial cancer and endometrial hyperplasia stain positively for the anti-LeY monoclonal antibody, whereas normal endometrium does not. Endometrial hyperplasia is a premalignant change associated with the eventual development of endometrial carcinoma. However, it can be difficult to differentiate hyperplasia from normal endometrium in cytology. This study illustrates the use of immunocytochemical cytology using anti-LeY monoclonal antibody to differentiate between endometrial hyperplasia and normal endometrium. Immunostaining using anti-LeY monoclonal antibody was performed on cytologic specimens obtained from 17 normal endometria, 25 endometria with endometrial hyperplasia, and 13 endometria with endometrial carcinoma. All normal endometria displayed negative staining for anti-LeY monoclonal antibody, whereas all endometria with endometrial carcinoma displayed positive staining. Of the endometrial hyperplasia cases, 21 displayed positive staining. However, four displayed negative staining due to the small number of cells available for diagnosis. We believe that immunostaining cytology using anti-LeY monoclonal antibody is a useful method for differentiating between normal endometrium and endometrial hyperplasia.