Endocrine Abstracts

Aim: Radioactive iodine (RAI) is one of the treatment approaches in Graves and toxic nodular or multinodular goiter (TNG/TMNG) with low cost and high efficacy. In this study, we aimed to evaluate ultrasonographical and cytological features of thyroid nodules in patients who were treated with radioactive iodine for hyperthyroidism years ago.

Methods: Patients who had a history of RAI treatment for hyperthyroidism and had thyroid nodules that were evaluated with fine needle aspiration biopsy (FNAB) were included in the study. Ultrasonographical features, and cytological and histopathological results of nodules were obtained from the records.

Results: There were 27 patients (22 female and 5 male) with a mean age of 59.3±13.5. The indication for RAI treatment was Graves in 5 (18.6%), TNG/TMNG in 16 (69.2%) and unknown in 6 (22.2%) patients. A total of 48 thyroid nodules were evaluated with FNAB and cytological diagnosis were benign in 24 (50.0%), nondiagnostic in 15 (31.2%), atypia of undetermined significance in 5 (10.4%), suspicous for malignancy in 2 (4.2%) and malignant in 2 (4.2%) nodules. Mean duration between RAI treatment and FNAB was 76.4±63.1 months. Thyroidectomy was performed in 10 patients and 5 were benign (50.0%) and 5 (50.0%) were malignant histopathologically. FNAB result was benign in 1 (20.0%), atypia of undetermined significance in 1 (20.0%), suspicious for malignancy in 1 (20.0%) and malignnt in 2 (40.0%) nodules with malignant histopathology. Ultrasonography features of 31 cytologically/histopathologically benign and 5 cytologically/histopathologically malignant nodules were compared. Rates of nodules with anteroposterior/transverse diameter ratio higher than 1, solid structure, presence of peripheral halo, marginal irregularity and microcalcification were similar in benign and malignant nodules (P=0.303, P=0.684, P=0.829, P=0.973 and P=0.621, respectively). There were 1 (20.0%) isoechoic, 1 (20.0%) hypoechoic and 3 (60.0%) iso-hypoechoic nodules among malignant nodules, while 24 (77.4%) of benign nodules were isoechoic, 3 (9.7%) were hypechoic and 4 (12.9%) were isohypoechoic (P=0.025). Macrocalcification was observed in 4 (80.0%) of malignant and 10 (32.3%) of benign nodules (P=0.042).

Conclusion: In patients treated with RAI due to hyperthyroidism, thyroid nodules with suspicious ultrasonography features, particulary hypoechoic appearence and presence of macrocalcification, should be evaluated with FNAB irrespective of the period after RAI treatment. Atypia related with previous RAI treatment might cause diagnostic problems in cytological evaluation.