Ovarian metastasis from thyroid carcinoma 12 years after partial thyroidectomy mimicking struma ovarii: report of a case.

A 29-year-old woman experienced abdominal swelling 12 years after undergoing partial thyroidectomy for follicular carcinoma of the thyroid with vascular invasion and 6 months after a right cerebral tumor that had caused hemiplegia had been excised. Laparotomy disclosed a solid and cystic right ovarian tumor, 17 cm in greatest dimension, and a 12-cm tumor of the right adrenal gland. Microscopic examination showed a malignant tumor of the thyroid follicular type with frequent mitotic figures; other teratomatous elements were absent. Because of the interval since the thyroid cancer, the diagnosis of a malignant struma ovarii was initially considered. The patient rapidly developed widespread metastatic disease and died, supporting the interpretation that the ovarian tumor was a metastasis from the thyroid neoplasm. This case illustrates that when other teratomatous elements are not identified, the diagnosis of malignant struma ovarii should be made only when the possibility of spread from a prior thyroid neoplasm, possibly one treated many years previously, has been excluded.