Preoperative diagnosis of malignant transformation in mature cystic teratoma of the ovary.

OBJECTIVE: Malignant transformation of mature cystic teratomas (MCT) of the ovary is extremely rare. There are no established criteria of diagnosis before surgery for carcinoma arising from MCT of the ovary. Thus, we analyzed retrospectively tumor size and preoperative values of tumor markers in patients with MCT and investigated the possibility of preoperative diagnosis.

METHODS: This was a retrospective case series of 278 patients with MCT of the ovary. Data were obtained from hospital charts and the pathology registry. Average tumor size (greatest diameter) was determined by the preoperative findings of both MRI and ultrasound examination.

RESULTS: Malignant transformation was seen in five patients (11%) among those whose tumor was > or = 10 cm in diameter, four patients (23%) among those whose pretreatment serum SCC level was > or = 2.0 ng/ml, two patients (13%) among those over 60 years of age and five patients (2%) with a tumor on one side. Mean tumor size and serum SCC level were significantly higher than those of benign MCT.

CONCLUSIONS: We conclude that patients over 60 years old who have unilateral MCT with SCC value of < or = 2.0 ng/ml and > or = 10 cm tumors may be a high-risk group for malignant transformation.