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.

Decidualization; Malignant transformation; Endometriosis

[1] Weiner Z., Thaler I., Beck D., Rottem S., Deutsch M., Brandes J.M.: "Differentiating malignant from benign ovarian tumors with transvaginal color flow imaging". Obstet. Gynecol., 1992, 79, 159.

[2] Tanaka Y.O., Yoshizako T., Nishida M., Yamaguchi M., Sugimura K., Itai Y.: "Ovarian carcinoma in patients with endometriosis: MR imaging findings". Am. J. Roentgenol., 2000, 175, 1423.

[3] Kobayashi F., Monma C., Nanbu K., Konishi I., Sagawa N., Mori T.: "Rapid growth of an ovarian clear cell carcinoma expressing LH/hCG receptor arising from endometriosis during early pregnancy". Gynecol. Oneal., 1996, 62, 309.

[4] Sugiyama T., Nishida T., Kataoka A., Okura N., I wanaga S., Yakushiji M.: "A pregnant woman with clear cell adenocarcinoma of the ovary arising from endometriosis and with benign and borderline adenofibroma of the clear cell and endometrioid types" Eur. J. Obstet. Gynecol. Reprod. Biol., 1997, 72, 47.

[5] Makrydimas G., Sotiriadis A., Paraskevaidis E., Pavlidis N., Agnantis N., Lolis D.: "Clear cell ovarian carcinoma in a pregnant woman with a history of infertility, endometriosis and unsuccessfol IVF treatment". Eur. J. Gynaecol. Oneal., 2003, 24, 438.

[6] Steed H., Chapman W., Laframboise S.: "Endometriosis-assoc1- ated ovarian cancer: a clinicopathologic review". J. Obstet. Gynaecol. Can., 2004, 26, 709.

[7] Varma R., Rollason T., Gupta J.K., Maher E.R.: "Endometriosis and the neoplastic process". Reproduction, 2004, 127, 293.

[8] Miyakoshi K., Tanaka M., Gabionza D., Takamatsu K., Miyazaki T., Yuasa Y. et al.: "Decidualized ovarian endometriosis mimicking malignancy". Am. J. Roentgenol., 1998, 171, 1625.

[9] Fruscella E., Testa A.C., Ferrandina G., Manfredi R., Zannom G.F., Ludovisi M. et al.: "Sonographic features of decidualized ovarian endometriosis suspicious for malignancy". Ultrasound Obstet. Gynecol., 2004, 24, 578.

[10] Sammour R.N., Leibovitz Z., Shapiro I., Degani S., Levitan Z.,Aharorn A. et al.: "Decidualization of ovarian endometriosis during pregnancy mimicking malignancy". J. Ultrasound Med., 2005, 24, 1289.

[11] Matsuoka Y., Ohtomo K., Araki T., Kojima K., Yoshikawa W., Fuwa S.: "MR imaging of clear cell carcinoma of the ovary". Eur. Radial., 2001, 11, 946

[12] Tanaka Y.O., Shigemitsu S., Nagata M., Shindo M., Okamoto Y., Yoshikawa H. et al.: "A decidualized endometrial cyst in a pregnant woman: a case observed with a steady-state free precession imaging sequence". Magn. Reson. Imaging, 2002, 20, 301.