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 imrpress.com as a courtesy and upon agreement with S.O.G.
Case study of a pregnant woman with decidualized ovarian endometriosis whose preoperative findings suggested malignant transformation
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.