Unusual Case of Metastatic Functional Thyroid Carcinoma Treated with Radioactive Iodine Described

The December 2017 issue of the Journal of the Endocrine Society includes an unusual case report of a patient with thyrotoxicosis due to functional thyroid carcinoma and Graves disease, who was treated successfully with radioactive iodine (RAI).

The paper, by Ari Geliebter, MD, et al., describes a 79-year-old woman came to the hospital with weakness in her upper and lower extremities. She had a remote history of hemithyroidectomy and current hyperthyroidism. “Hospital evaluation revealed a suppressed thyroidstimulating hormone (TSH) level, positive test for thyroid-stimulating immunoglobulins, as well as a thyroid nodule, lung masses, and a 4.4- cm gluteal mass,” the authors write.

A fine-needle aspiration revealed metastatic differentiated thyroid carcinoma, and she had a completion thyroidectomy and her gluteal mass was removed. However, her hyperthyroid status remained. “The patient in this report had a functional thyroid carcinoma: She remained hyperthyroid even after thyroidectomy and removal of the large gluteal metastasis, and had extremely high uptake of RAI in the metastatic tissue,” the authors write.

The authors go on to write that this case shows that thyrotoxicosis in the setting of metastatic differentiated thyroid carcinoma could actually be the result of functional thyroid carcinoma. “Functional thyroid carcinoma is a rare but well-described phenomenon and must be considered when evaluating thyroid carcinoma with concurrent hyperthyroidism,” they write. “Treatment with RAI may be particularly beneficial in these patients in achieving long-term disease control.”