Painful Radiation Thyroiditis after 131 I Therapy for Graves' Hyperthyroidism: Clinical Features and Ultrasonographic Findings in Five Cases

Radiation thyroiditis caused by I therapy for Graves' hyperthyroidism is asymptomatic in most patients and is rarely associated with pain or fever. Currently, there are few reports on the ultrasonographic findings of radiation thyroiditis after I therapy for Graves' hyperthyroidism. We herein report 5 cases with painful radiation thyroiditis (including 2 febrile cases) after I therapy for Graves' hyperthyroidism. The cases included 4 women, aged 49, 50, 76, and 81 years, and 1 man, aged 60 years. Anterior neck pain developed 0-10 days after I administration (fixed dose of 481 MBq). Each patient visited our clinic 0-4 days after the development of anterior neck pain. The thyroid glands were noticeably enlarged (increasing from 18 g at I administration to 35 g after the development of anterior neck pain in 1 patient, and from 20 to 33 g, 21 to 39 g, 21 to 51 g, and 40 to 51 g in the other patients) and tender. The echogenicity of the thyroid parenchyma was increased, and the parenchyma was more heterogeneous. Granular hyperechoic lesions were scattered throughout the thyroid gland in the most severe case. The border between the thyroid gland and the surrounding tissue was blurred, and the surrounding tissue was hyperechoic. Painful radiation thyroiditis should be reacknowledged as one of the complications of I therapy for Graves' hyperthyroidism. Ultrasonography demonstrated the characteristic changes caused by I-induced radiation thyroiditis.