IMR Press / EJGO / Volume 27 / Issue 3 / pii/2006176

European Journal of Gynaecological Oncology (EJGO) is published by IMR Press from Volume 40 Issue 1 (2019). Previous articles were published by another publisher on a subscription basis, and they are hosted by IMR Press on as a courtesy and upon agreement with S.O.G.

Open Access Case Report

Case study of a pregnant woman with decidualized ovarian endometriosis whose preoperative findings suggested malignant transformation

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1 Department of Obstetrics and Gynecology, Yamanashi Red Cross Hospital, Japan
2 Department of Obstetrics and Gynecology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Japan
Eur. J. Gynaecol. Oncol. 2006, 27(3), 301–303;
Published: 10 June 2006

Background: Because both decidualization and malignant transformation of endometriosis are characterized by mural nodules on the wall of the cyst, the preoperative differential diagnosis is reportedly difficult. Case: A 31-year-old woman was referred to our hospital at ten weeks of gestation. Sonographic examination revealed an intrauter­ine gestational sac and ovarian endometrial cyst. At 21 weeks of gestation, characteristic findings associated with malignant trans­formation of ovarian endometriosis were seen on color-flow Doppler sonography and contrast magnetic resonance imaging. Under the diagnosis of malignant transformation of ovarian endometriosis, right salpingo-oophorectomy was performed at 22 weeks' gestation. However, histopathologic examination revealed ovarian endometriosis with marked decidual changes but no evidence of malignancy. Conclusion: During pregnancy, intracystic vascularized excrescences of an endometrial cyst indicate not only malignant trans­formation but also decidualization. Thus, the preoperative differential diagnosis is reportedly difficult. However, the present find­ings of decidualization on magnetic resonance imaging seemed to be slightly different from those of malignant transformation, and therefore, might help distinguish decidualized endometriosis from malignant transformation preoperatively.

Malignant transformation
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