A CASE OF METASTATIC FOLLICULAR CARCINOMA OF THE THYROID. CAUSING HYPERTHYROIDISM (T3 TOXICOSIS)

Abstract

We experienced a rare case of lung, and bone metastases from follicular carcinoma of the thyroid, presenting with hyperthyroidism induced by triiodothyronine (T3), which was secreted from metastatic lesions after surgery for primary lesion.A 42-year-old female suffering from a tumor of the neck for past 3 years consulted us in Mar. 1977. It was a thyroid tumor of 7 by 5 cm in size, elastic hard and smooth surface in palpation. She didn't have thyroid dysfunction. Under a clinical diagnosis of thyroid adenoma, left hemithyroidectomy was performed. Although the tumor was histologically diagnosed being follicular carcinoma, she was followed without any other treatments. Three years after surgery, modified neck dissection was done for regional lymph nodes metastases, and TSH suppression therapy was added. Seven years after the first surgery, lung and liver metastases were found and remained thyroid was removed for the 131I irradiation. Following 3 years, twice 131I and external irradition for pain control of sacral metastasis were performed. TSH suppression therapy by T3 (25 μg/day) and T4 (100 to 200 μg/day)administration was also continued, but the metastatic lesions gradually enlarged. Eleven years after the first surgery, the elevation of serum T3 and TSH receptor antibody were found, and one year after that she manifestated palpitation as a symptom of hyperthyroidism. The stop of T3 and T4 administration failed to control the thyrotoxicosis, and methylmercaptoimidazol (30 μg/day) was needed. The patient died of respiratory insufficiency caused by the enlarged pulmonary metastasis.T3 production in the metastatic lesions and the increase of its release to blood according to tumor growth were thought to be main factors for hyperthyroidism in this patient. Autoimmune disorder also may participate in the occurrence of hyperthyroidism.