title: Prevalence of Endometriosis in Malignant Epithelial Ovarian Tumor.
abstract: BACKGROUND
  The present study aims to assess the prevalence and histological characteristics of endometriosis in different types of ovarian surface epithelial tumors.
  
  
  METHODS
  Microscopic slides of 110 ovarian tumors (89 malignant and 21 borderlines) were reviewed from 2008 to 2013 in two major gynecological centers affiliated with the Shiraz University of Medical Sciences, Shiraz, Iran. The presence or absence of endometriosis and transitions from atypical endometriosis to carcinoma were also histologically evaluated. Chi-square and t-test were used to compare the study groups.
  
  
  RESULTS
  The mean age of the patients was 49.93 ± 9.36 years in the Endometriosis-Associated Ovarian Carcinomas (EAOC) group and 50.18 ± 12.8 years in the non-EAOC group. Among the 110 patients, 28 (25.4%) had endometriosis. According to ovarian cancer subtype 67% (4/6) of clear cell adenocarcinoma, 65% (11/17) of endometrioid adenocarcinoma, 28% (7/25) of low grade serous adenocarcinoma, 4% (1/25) of high grade serous adenocarcinoma, 30% (4/13) of borderline serous tumor, and 25% (1/4) of mixed carcinoma had endometriosis. None of the mucinous borderline tumors and mucinous adenocarcinoma cases had endometriosis. Moreover, 23 cases had typical endometriosis, while 14 had atypical endometriosis. On the other hand, 19 cases had both typical and atypical endometriosis. Furthermore, transition from atypical endometriosis to carcinoma was seen in 11 cases.
  
  
  CONCLUSIONS
  Clear cell and endometrioid carcinoma are the most common types of EACO. Atypical endometriosis was more commonly seen in endometrioid and clear cell carcinomas which are included in type I ovarian cancer. Thus, it can be concluded that atypical endometriosis is a precursor for type I ovarian cancer.
authors.affiliation: Maternal-Fetal Medicine Research Center, Pathology Department, Shiraz University of Medical Sciences, Shiraz, Iran.
authors.forename: Mojgan
authors.initials: M
authors.lastname: Akbarzadeh-Jahromi
authors.affiliation: Pathology Department, Shiraz University of Medical Sciences, Shiraz, Iran.
authors.forename: Golsa
authors.initials: G
authors.lastname: Shekarkhar
authors.affiliation: Pathology Department, Shiraz University of Medical Sciences, Shiraz, Iran.
authors.forename: Fatemeh
authors.initials: F
authors.lastname: Sari Aslani
authors.affiliation: Transplant Research Center, Nemazi Hospital, Shiraz University of Medical Sciences, Shiraz, Iran.
authors.forename: Negar
authors.initials: N
authors.lastname: Azarpira
authors.affiliation: Pathology Department, Shiraz University of Medical Sciences, Shiraz, Iran.
authors.forename: Mina
authors.initials: M
authors.lastname: Heidari Esfahani
authors.affiliation: Obstetrics and Gynecology Department, Shiraz University of Medical Sciences, Shiraz, Iran.
authors.forename: Mozhdeh
authors.initials: M
authors.lastname: Momtahan
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D004715:Endometriosis / Q000453:epidemiology / Q000473:pathology*; D005260:Female; D006801:Humans; D008875:Middle Aged; D010051:Ovarian Neoplasms / Q000473:pathology*; D011230:Precancerous Conditions / Q000473:pathology*; D015995:Prevalence