Enhanced detection of atypical hyperplasia in endometrial polyps by PTEN expression

Endometrial hyperplasia is difficult to recognize within endometrial polyps because of the background of randomly distributed irregular glands. The loss of expression of the PTEN oncogene is characteristic of endometrial cancers and clinically significant hyperplasia. Using immunohistochemical staining for the PTEN protein, we studied 12 endometrial polyps that were noted to contain foci of complex hyperplasia or glandular crowding. Loss of PTEN staining was found in 3 cases, suggesting a precancerous lesion. Moreover, 2 of these cases were originally classified as complex hyperplasia without atypia and 1 as merely glandular crowding. Thus, in selected cases, the loss of PTEN expression in an area of glandular crowding can highlight biologically significant lesions and afford a more definitive diagnosis.