Malignant transformation of ovarian mature cystic teratoma.

There have been few studies concerning the clinical pathology of malignant transformation arising in ovarian mature cystic teratoma (MCT). Thus, the objective of this study is to determine clinicopathologic factors affecting survival in this rare tumor. From November 1992 to December 2002, 11 patients with malignant transformation arising in ovarian MCT were treated at Department of Obstetrics and Gynecology in Chonnam National University Hospital. Demographic characteristics, symptoms, signs, stage, mode of therapy, and results of follow-up were reviewed retrospectively. There were 11 cases of the malignant transformation of ovarian MCT out of 637 cases of MCT (1.7%). The average age was 50.6 years. Histologically, 7 out of the 11 cases were squamous cell carcinoma (63.7%). There were no specific clinical symptoms, but palpable abdominal mass was the most frequent complaint (five cases, 45.4%). As for the stage of disease, eight cases were in stage IA (72.7%), and the other three cases were in stage IC, IIB, and IIC, respectively. All the patients had surgery, and seven of them had adjuvant chemotherapy and two had adjuvant chemoradiation. All the patients in stage I survived until the period of follow-up, and their average survival time was 31.8 months. One patient in stage IIC died of intestinal obstruction within 9 months from the surgery. The mechanism of the malignant transformation arising in ovarian MCT is not clear, but considering the fact that 80% of MCTs are diagnosed during the reproductive age, malignant transformation seems to be related to the long-term presence of nonremoved MCT in the abdomen. Accordingly, it is considered helpful for preventing and early detection of the malignant transformation to have regular ovary examination through pelvic ultrasonogram during the reproductive age.