An unusual case of metastatic functional thyroid carcinoma with a remarkable treatment response to radioactive iodine

Ari Geliebter, Erika F. Brutsaert, Martin I. Surks

Research output: Contribution to journalArticle

1 Scopus citations

Abstract

Functional thyroid carcinoma is an unusual cause of thyrotoxicosis. We describe the clinical presentation and treatment of a patient with thyrotoxicosis due to functional thyroid carcinoma and Graves disease, and discuss potential mechanisms causing the thyrotoxicosis. A 79-year-old woman with a remote history of hemithyroidectomy and current hyperthyroidism came to the hospital with upper and lower extremity weakness. Hospital evaluation revealed a suppressed thyroid-stimulating hormone (TSH) level, positive test for thyroid-stimulating immunoglobulins, as well as a thyroid nodule, lung masses, and a 4.4-cm gluteal mass. Fine-needle aspiration of the gluteal mass revealed metastatic differentiated thyroid carcinoma. Even after completion thyroidectomy and excision of her gluteal mass, her hyperthyroid status continued when she was not receiving levothyroxine. A radioactive iodine uptake and scan revealed unusually high lung uptake of 40%, and she was successfully treated with radioactive iodine (RAI) despite complete TSH suppression. The patient developed hypothyroidism 2 months after RAI administration; 6 months after RAI administration, her thyroglobulin (Tg) levels had fallen from a peak of 1976 ng/mL to 1.4 ng/mL. She had no anti-Tg antibodies. Repeated positron emission tomography-computed tomography nearly 1 year after RAI treatment shows substantial regression in the lung nodules, and Tg measured by mass spectroscopy is undetectable. This case demonstrates that thyrotoxicosis in the setting of metastatic thyroid carcinoma may be the result of functional thyroid carcinoma and may be successfully treated with selective surgery and RAI administration.

Original languageEnglish (US)
Pages (from-to)1440-1444
Number of pages5
JournalJournal of the Endocrine Society
Volume1
Issue number12
DOIs
StatePublished - Dec 2017

Keywords

  • Functional thyroid carcinoma
  • Graves Disease
  • Hyperthyroidism
  • Radioactive iodine
  • Thyroid cancer

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism

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