[Atypical endometriosis: a clinicopathologic study of 163 cases]

To investigate the clinicopathologic features of atypical endometriosis (AEM) and to discuss the relationship between AEM and tumors.

A retrospective analysis was performed of 163 cases of AEM, which were retrieved from the Department of Pathology files at the Tianjin Central Obstetrics and Gynecology Hospital between Jan 2004 and Dec 2006. The pathologic changes of AEM including its glandular epithelium, stroma, background and the conditions coexisting with tumor were observed.

The AEM accounted for 4.38% (163/3724) of the endometriosis (EM) cases. Of 172 AEM foci of 163 patients, 168 were in the ovary, and the other 4 were in the fallopian tube, cervix and uterine serosa respectively. The rate of ovarian AEM was 6.81% of endometriosis. AEM associated with tumour was found in 26 cases (15.95%) and among 27 of ovarian AEM, 15 were malignant, 9 borderline and 3 benign. The AEM epithelia were mainly arranged in the form of surface epithelium. They present with characteristic features of moderate to marked pleomorphism, epithelial tufting and bud structures by microscopy. The walls of AEM cyst were presented with three layers of epithelium, endometrioid stroma and fibrosis-collagen. The endometrioid stroma were usually thin in contrast to the fibro-collagen tissue, which was often thick with scarred background. The transformation from AEM to tumor was found in most of the malignant tumors (14/15, 93%).

AEM lesions hold some features of both EM and tumor, which may have a relatively higher potential for tumorigenesis and canceration. The process of damage and repair in EM foci during a long course may play a role in the development of EM into AEM and finally into tumor.