RESUMO
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. This condition is termed "peritoneal strumosis." SUMMARY: We report a 49-year-old woman with struma ovarii complicated by peritoneal strumosis with thyrotoxicosis. After surgical resection of the struma ovarii and peritoneal strumosis the patient became euthyroid. CONCLUSION: To the best of our knowledge this is the first report of a patient with peritoneal strumosis complicated by thyrotoxicosis. The relative contribution to circulating thyroid hormones by the patient's struma ovarii as compared to the peritoneal strumosis is not known.