Abstract
BackgroundWhile ovarian mature cystic teratomas are benign ovarian germ-cell tumors and the most common type of all ovarian tumors, the formation of fistulas into surrounding organs such as the bladder and the intestinal tract is extremely rare. This report documents a case of ovarian mature cystic teratoma with a rectal fistula, thought to be caused by local inflammation.Case descriptionA pelvic mass was diagnosed as an ovarian mature cystic teratoma of approximately 10 cm in diameter on transvaginal ultrasound and magnetic resonance examinations. Endoscopic examination of the lower gastrointestinal tract to investigate diarrhea revealed an ulcerative lesion with hair in the rectal wall adjacent to the ovarian cyst, and formation of a fistula from the ovarian teratoma into the rectum was suspected. Laparotomy revealed extensive inflammatory adhesions between a left ovarian tumor and the rectum. Left salpingo-oophorectomy and upper anterior resection of the rectum were performed. The final pathological diagnosis was ovarian mature cystic teratoma with no malignant findings, together with severe rectal inflammation and fistula formation with no structural disorders such as diverticulitis of the colon or malignant signs.DiscussionThe formation of fistulas and invasion into the neighboring organs are extremely rare complications for ovarian mature cystic teratomas. The invasion of malignant cells into neighboring organs due to malignant transformation of the tumor is reported as the cause of fistula formation into the neighboring organs. A review of 17 cases including the present case revealed that fistula formation due to malignant transformation comprised only 4 cases (23.5 %), with inflammation as the actual cause in the majority of cases (13 cases, 76.5 %).ConclusionAlthough malignancy is the first consideration when fistula formation is observed between ovarian tumors and surrounding organs, in mature cystic teratoma, local inflammation is more likely than malignant transformation.
Highlights
While ovarian mature cystic teratomas are benign ovarian germ-cell tumors and the most common type of all ovarian tumors, the formation of fistulas into surrounding organs such as the bladder and the intestinal tract is extremely rare
The invasion of malignant cells into neighboring organs due to malignant transformation of the tumor is reported as the cause of fistula formation into the neighboring organs
A review of 17 cases including the present case revealed that fistula formation due to malignant transformation comprised only 4 cases (23.5 %), with inflammation as the actual cause in the majority of cases (13 cases, 76.5 %)
Summary
Ovarian mature cystic teratomas are the most common ovarian tumor, comprising 10–25 % of all cases (Tandon et al 2010). Shiels et al (1986) consider the following steps to be involved in the pathogenesis of fistula formation: (1) rupture or perforation of the cyst, (2) small leakage from the cyst causing dense adhesion between the cyst and the surrounding organs, (3) circulatory disturbance of the walls of these structures due to the resultant necrosis and inflammation, and (4) formation of fistulas in the walls of these structures They have mentioned that rupture or perforation of the cyst is likely caused by circulatory disorders or infection due to factors such as partial torsion, malignant transformation, and mechanical forces. We too performed extended surgery in consideration of the possibility of a malignant tumor, but with the knowledge that inflammation is an extremely common cause of fistula formation from ovarian mature cystic teratomas, more limited surgery might have been possible, and we must reflect upon this point
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