title: Decidualization of ovarian endometriosis during pregnancy mimicking malignancy: report of three cases with a literature review.
abstract: BACKGROUND
  Intracystic papillary excrescence is a characteristic morphological feature of ovarian malignancy. A few recent reports have demonstrated that ovarian endometriotic cysts, undergoing decidualization during pregnancy, occasionally show excrescence, necessitating surgery during pregnancy; however, this phenomenon is not well recognized among clinicians.
  
  
  METHODS
  Three pregnant women with decidualized ovarian endometriosis showed excrescence. Both ultrasound and magnetic resonance imaging (MRI) preoperatively suggested the presence of underlying ovarian endometriotic cysts in 2 women, but not in the other. Intracystic papillary excrescence prompted us to perform laparotomy at 14, 14, and 19 weeks of pregnancy, respectively, with 1 woman aborting in the 21st week, and with 2 delivering healthy term infants. Histological examination confirmed the diagnosis of decidualized ovarian endometriotic cysts in all 3 patients.
  
  
  CONCLUSIONS
  We provide the first report of pregnant women in whom excrescence occurred from ovarian endometriotic cysts without preoperative evidence. Decidualized ovarian endometriosis, even without preoperative morphological features of endometriosis, should be added to the differential diagnosis of ovarian malignancy during pregnancy.
authors.affiliation: Department of Obstetrics and Gynecology, Jichi Medical University, Tochigi, Japan.
authors.forename: Shizuo
authors.initials: S
authors.lastname: Machida
authors.forename: Shigeki
authors.initials: S
authors.lastname: Matsubara
authors.forename: Michitaka
authors.initials: M
authors.lastname: Ohwada
authors.forename: Manabu
authors.initials: M
authors.lastname: Ogoyama
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Kuwata
authors.forename: Takashi
authors.initials: T
authors.lastname: Watanabe
authors.forename: Akio
authors.initials: A
authors.lastname: Izumi
authors.forename: Mitsuaki
authors.initials: M
authors.lastname: Suzuki
mesh_terms: D000328:Adult; D003656:Decidua / Q000473:pathology; D003937:Diagnosis, Differential; D004715:Endometriosis / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery; D005260:Female; D006801:Humans; D010048:Ovarian Cysts / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery; D011247:Pregnancy; D011252:Pregnancy Complications, Neoplastic / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery; D014463:Ultrasonography; D055815:Young Adult