Malignant transformation of mature cystic teratoma of the ovary: experience at a single institution.

OBJECTIVES: Malignant transformation of mature cystic teratoma (MCT) of ovary is very rare. Therefore, the clinicopathologic characteristics, treatment and prognostic factors are not yet well established. The aim of this study was to review our experience with this malignancy and previously published reports in the literature.

STUDY DESIGN: A review of pathologic reports for 2019 patients with ovarian MCT and 937 patients with primary ovarian cancer who were treated at the Asan Medical Center, Korea, from 1989 to 2007 identified 16 patients with malignant transformation from MCT. A retrospective chart review of these patients and a review of the literature were performed.

RESULTS: The incidence rate of malignant transformation was 0.8% of all ovarian MCT. It accounted for 1.7% of all primary ovarian cancer. Squamous cell carcinoma was the most common histologic type, comprising 75%. The median age of the 16 patients was 50 years (range, 29-75 years). Mean tumor size was 14.5 cm (range, 5-26 cm). Twelve patients had some solid portions in the cyst containing fat fluid, hair, and/or calcification. According to the review of the patients in our study and of the literature, early detection and complete surgical resection are important for long-term survival. It seems that adjuvant chemotherapy or concurrent chemoradiation therapy have roles in treating this malignancy.

CONCLUSIONS: Early detection is important for long-term survival. Old age, large tumor size, and solid portion in mature cystic teratoma seem to predict the malignant transformation of mature cystic teratoma.