Ovarian heterotopic pregnancy clinically mimicking endometrioma

2 Departments of Gynaecology and Obstetrics, Karaelmas University, Faculty of Medicine, ZONGULDAK, TURKEY DOI: 10.5146/tjpath.2010.01002 Viewed: 6155 - Downloaded : 2770 The most common site of implantation in heterotopic and ectopic pregnancies is the Fallopian tube. Although less common, implantation may also occur in the tubal fimbriae, abdominal cavity, uterine interstitium, and uterine cornua. However, ovarian heterotopic pregnancies are quite rare[1-9]. Ovarian heterotopic pregnancy may be clinically and radiologically confused with tubal ectopic pregnancy, hemorrhagic corpus luteum cysts, or endometriotic cysts. Ectopic pregnancy should be considered in patients who present with pelvic pain and have risk factors, regardless of whether they have menstrual irregularities. Serum beta hCG levels and a careful radiologic study are important for diagnosis[3,5,9]. Macroscopically, ovarian heterotopic pregnancy appears as a space-occupying hemorrhagic mass in the ovary with a blue−purple color. During surgery, approximately two-thirds of these cases are confused with hemorrhagic corpus luteum[3-6]. In the present case, no symptoms or clinical signs suggestive of ovarian heterotopic pregnancy was detected during routine prenatal check-ups. During the caesarean section performed during the 36th week of the pregnancy due to placenta previa, the discovery of a hemorrhagic mass in the left ovary and a pre-diagnosis of endometrioma prompted the surgeons to perform a wedge resectomy. The histomorphological features of placental tissue from the ectopic fetus were consistent with a pregnancy in its first trimester. Placental tissues appeared to be surrounded by inflammatory cells and fibrous tissue in the hematoma. The remnants of the chorionic villi were fibrotic and degenerated, and very few trophoblastic cells were observed. These findings indicate that the ovarian heterotopic pregnancy had ended in the first trimester, which is consistent with the literature, along with involution of the placental tissue. Ovarian heterotopic pregnancies typically exhibit an asymptomatic course due to ending of the pregnancy at an early stage and involution of the placental tissue. The clinical diagnosis of heterotopic pregnancy should be supported by a histopathological diagnosis. Histopathological examination reveals chorionic villouslike structures, trophoblastic cells, and/or membranes within the hematoma. Some ectopic pregnancies may form a chronic inflammatory mass, with trophoblastic tissue involution. This condition is known as a ‘chronic ectopic pregnancy,' and many samples are required to detect the few degenerated villi. Demonstrating trophoblastic cells by immunohistochemical techniques contributes significantly to diagnosis[1-9]. In the present case, the histomorphological appearance was confused with an organised hematoma, due to placental tissue that had undergone involution. However, the immunohistochemical determination of keratin, hPL, hCG, and a few trophoblastic cells verified the diagnosis of ovarian heterotopic pregnancy. Treatment of these cases is complicated by the coexisting intrauterine pregnancy. Removal of the gestational sac by laparoscopy or laparotomy is the treatment of choice. However, selective embryo reduction by direct injection of potassium chloride or hyperosmolar glucose into the ectopic gestational sac is another treatment option[9-13]. In conclusion, ovarian ectopic (or heterotopic) pregnancy should be considered in the differential diagnosis of hemorrhagic ovarian masses, particularly in pregnancies resulting from assisted reproductive technologies. In such cases, establishing a preoperative diagnosis is very difficult. 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