Résumé
Malignant transformation develops in a little less than 2% of mature cystic teratomas. A wide variety of malignant tumors may arise within benign mature cystic teratomas, and the most common of these is squamous cell carcinoma, which account for 75~85%. In general, the tumors are in an advanced stage and the prognosis is poor as most patients die within a year. However, when the tumor is confined to the ovary, they have a good prognosis and the 5-year survival rate is 63~83%. We experienced three cases of squamous cell carcinoma arising in mature cystic teratoma. Two of the carcinomas occurred in postmenopausal women: 58-(case 1) and 66-(case 2) year-old, and were confined to the ovaries. They were alive 37 months and 18 months after the operation, respectively. The third case was a 45-year-old premenopausal woman who had an extraovarian extension of the tumor and early recurrence within two months. Histologically, cases 1 and 3 were conventional well to moderately differentiated squamous cell carcinomas and case 2 showed a well-differentiated squamous cell carcinoma with exuberant proliferating trichilemmal tumor-like areas.