Background: Struma ovarii is a highly specialized form of mature ovarian teratoma consisting of thyroid tissue and exhibiting all the histological features of the thyroid gland. Malignant transformation of thyroid tissue in struma ovarii and metastasis are extremely uncommon. In rare cases, benign thyroid tissue may spread to the peritoneal cavity, and pathologic examination of the peritoneal implants shows multiple nodules of varying sizes of mature thyroid tissue similar to struma ovarii.
Summary: We report a 30-year-old woman with struma ovarii complicated by peritoneal dissemination with thyrotoxicosis. After surgical resection of the struma ovarii and peritoneal implants the patient became euthyroid.