Abstract
BACKGROUND: Graves disease (GD) is an autoimmune condition characterized by the presence of antibodies against the thyrotropin receptor (TRAB), which stimulate the thyroid gland to produce excess thyroid hormone. Theoretically, TRAB could stimulate highly differentiated thyroid cancer tissue and/or metastases to produce thyroid hormone. CASE: A 68-year-old male, with weight loss and palpitations, was diagnosed with thyrotoxicosis. A later MRI, due to persistent shoulder pain, revealed multiple bone metastases. A biopsy was diagnostic for follicular variant of papillary thyroid carcinoma, and total thyroidectomy was performed. One week after thyroidectomy the patient was admitted with severe hyperthyroidism. TRAB was >40 IU/mL (normal <0.7 IU/mL). High-dose antithyroid drug treatment was followed by high-dose radioactive iodine-131 (RAI) and local radiotherapy covering the right shoulder. Antithyroid drug treatment continued until after the fourth RAI dose. Hypothyroidism did not occur until following the fifth RAI treatment. SUMMARY AND CONCLUSIONS: We present a patient initially diagnosed with thyrotoxicosis and subsequently with metastatic follicular variant of papillary thyroid cancer. It is suggested that TRAB stimulated the highly differentiated extrathyroidal metastatic thyroid tissue to produce excessive amounts of thyroid hormone, delayed diagnosis, and potential aggravation of the course of thyroid cancer.