Torsion of bilateral ovarian dermoid cysts with one parasitic teratoma at the omentum

Objective: To report a rare case of bilateral torsion of ovarian dermoid cysts as well as one parasitic teratoma at the omentum. Case Report: A 40-year-old female presented with lower abdominal pain. Physical examination detected one huge abdominal mass from the pelvic area up to the level of the umbilicus. An ultrasound examination revealed two abdominal masses; the central mass was an irregular hyperechogenic cystic tumor (25 cm), and the other (4 cm), which had the same echo appearance, was located in the right adnexa. Kidney-ureter-bladder radiography illustrated a calcified ring over the right lower abdomen. Nevertheless, the concentrations of five tumor markers were all within normal ranges. After laparotomy, we found that the two masses were of ovarian origin, both with torsion to the contralateral side, and the smaller mass had a blood supply from the omentum, i.e. a parasitic teratoma at the omentum. Conclusion: Autoamputation and reimplantation of an ovarian dermoid cyst is the most common etiology of a parasitic omental teratoma. For omental mature cystic teratoma, simple resection is the best choice of treatment.