Benign ovarian dermoid cyst complicated with rectal fistula formation: an unusual case.

BACKGROUND: Fistulation in benign cystic teratomas has not been commonly reported in the literature. We present a case of a benign ovarian dermoid cyst complicated with a recto-ovarian fistula.

CASE REPORT: A 30-year-old nonpregnant woman admitted to the gynecological outpatient clinic because of lower abdominal pain and purulent diarrhea. Gynecological examination and ultrasonography revealed a 10-cm heterogeneous cystic mass in the left ovary. Abdominopelvic CT scan revealed a left ovarian mass (10 x 9 cm) thought to be a dermoid cyst, which was seen to penetrate the proximal part of the rectum. Left adnexectomy and low anterior rectum resection were performed. The pathological evaluation suggested benign ovarian dermoid tumor penetrating the rectum wall.

CONCLUSION: Fistula formation by a dermoid ovarian cyst is not always related to malignant transformation of the cyst. In addition to factors such as torsion, infection, trauma, and chronic pressure during labor, spontaneous rupture of the dermoid cyst resulting in leakage of fluid could be the cause of fistula formation.