Malignant struma ovarii. A case report and literature review.

A woman developed papillary adenocarcinoma in a struma ovarii. The focus of malignancy was within a benign struma found at laparotomy for a pelvic mass. The patient had a previous history of bilateral cystic teratomas. The tumor was composed of papillae of crowded, pleomorphic cells with minimal cytoplasm but a wide range of chromatin patterns. Immunoperoxidase staining for thyroglobulin revealed positive regions in both the benign and malignant areas of tumor. A 15-year review of cystic teratomas in the state of Colorado revealed a frequency of 0.3% for malignant struma ovarii.