Malignant transformation in benign cystic teratomas: dermoids of the ovary.

Twenty-four cases with a malignant change involving one of the elements of a benign ovarian dermoid cyst are reported. Squamous cell carcinoma was most frequent. Eighteen patients (75%) were over 50 years of age. The prognosis is rather good if the tumor has not extended beyond the capsule, 85% surviving without detectable disease after 4 months to 9 years. The prognosis is very poor if the tumor has extended beyond the capsule, over 80% dying within 2 years. Hysterectomy with bilateral salpingo-oophorectomy is the treatment of choice, certainly in older patients. Additional treatment with cytostatics or radiation seems to have little influence on the prognosis.