Resistance to thyroid hormone (RTH) is a genetic disease characterized by a reduced target tissue responsiveness to thyroid hormones and increased or normal TSH level despite elevated levels of thyroid hormones. This condition is mainly caused by mutations of thyroid hormone receptor beta (THRB) gene. The role of THRB mutation in carcinogenesis is still unclear. In here, we report a case of papillary thyroid carcinoma (PTC) with RTH, with a past medical history of subtotal thyroidectomy due to diffuse goiter. A 61-year-old woman was referred to our hospital with recurrence of goiter and displayed elevated serum thyroid hormones and unsuppressed TSH levels. Genetic analysis of THRB identified a missense mutation, (Exon 7, rs3752874, c.735C>T) leading to diagnosis of RTH. The neck ultrasonography showed an isoechoic 9×11×11 mm sized nodule, a cystic 13×13×15 mm sized nodule with microcalcification in the right lobe, a 7×9×9 mm sized nodule with thin hypoechoic ring around in the right isthmus, a 9×12×14 mm sized, iso-hypoechoic,uniformly restricted nodule with cystic component in the left isthmus and a 17×25×29 mm sized hypoechoic nodule in the left lobe. Ultrasound-guided fine-needle aspiration biopsy was performed for microcalcific nodule in the right lobe. Cytologic examination of fine needle aspiration biopsy specimen was suspicious for follicular neoplasm. Total thyroidectomy was performed. Pathologic examination of thyroid tissue revealed capsulated oncocytic variant papillary thyroid cancer in 32 mm sized nodule in the left lobe and 7 and 2 mm sized nodules in the right lobe. The patient was scheduled for radioactive I-131 treatment. There is no consensus on the management of thyroid carcinoma in patients with RTH. The main concerns are the relationship between differentiated thyroid cancer and thyroid hormone resistance, whether it is a coincidence, how to suppress TSH levels, which treatment regimen should be chosen and which parameters should be considered in the follow-up of these patients. Further studies are required to find scientific answers to these questions.
20 - 23 May 2017
European Society of Endocrinology