Displacement of Ovarian Mature Cystic Teratoma following Rupture during Pregnancy: Case report

Approximately 1-4% of pregnant women develop ovarian tumors, 37% of which are mature cystic teratomas. The tumor commonly arises from the ovary; however, it may appear up to the midportion of the genital ridge during primordial germ cell migration, typically in the midline of the body. We describe a case of an ovarian mature cystic teratoma that was markedly displaced upward due to adhesions that formed following a minimal amount of leakage from the tumor contents. The high and extrapelvic localization of the tumor interfered with the determination of the correct preoperative diagnosis. The patient visited our department at 29 weeks of gestation with a chief complaint of severe right lower abdominal pain. Magnetic resonance imaging (MRI) revealed that the abdominal tumor containing fat and calcifications at the level of the fourth lumbar vertebra. The pain was relieved by administration of acetaminophen, and the patient received conservative management. After her vaginal delivery at 39 weeks of gestation, the tumor was found to be located at the same position that it was during pregnancy. MRI after delivery showed a normal involuted uterus and normal-appearing ovaries. The right ovary was located between the uterus and the tumor at the level of the fourth lumbar vertebra. The localization of the tumor suggested an extra-ovarian origin. The patient underwent laparoscopic surgery six months postpartum. The tumor was connected to the right ovary through a whitish streak; a cystectomy was performed. The pathological diagnosis was a mature cystic teratoma. Our postoperative diagnosis was a mature cystic teratoma arising from the right ovary. Our hypothesis to explain the localization of the tumor was: a small amount of leakage associated with the rupture at 29 week's gestation resulted in adhesions between the tumor and the parietal peritoneum. During uterine involution, the tumor did not descend due to adhesions to the parietal peritoneum and the omentum. The displacement of the tumor required a differential diagnosis for tumor origin: ovary, accessory ovary, supernumerary ovary, ovarian implant, and extra-ovarian tissue such as mesentery. When laparoscopic surgery is attempted in cases such as this, preoperative consideration is necessary regarding the appropriate insertion site for the ports.