Thyroid carcinoma risk in patients with hyperthyroidism and role of preoperative cytology in diagnosis

The aim of this study was to determine the frequency of thyroid carcinoma in patients with hyperthyroidism and evaluate the role of preoperative ultrasonography (US) guided thyroid fine needle aspiration biopsy (FNAB) in diagnosis of thyroid carcinoma in these patients.

Three hundred twenty-five hyperthyroid patients--119 with toxic multinodular goiter (TMNG), 47 with autonomous functioning toxic nodule (AFTN) and 159 with Graves Disease (GD)--were included in this study. All patients were evaluated with US and in all patients with nodules, US guided FNAB was carried out.

Among 159 patients with GD, 62 were without nodules. Totally, 583 nodules in 263 patients were sampled by FNAB. Cytologic results of nodules were as follows: 87.7% benign, 6.2% inadequate, 4.3% suspicious and 1.9% malignant. Postoperatively, 42 (12.9%) patients were diagnosed as thyroid carcinoma histopathologically. Thyroid carcinoma was detected postoperatively in all patients with malignant cytology, in 47.8% of patients with suspicious cytology and in 44.4% of patients with inadequate cytology. Moreover, in 13 patients with benign cytology and in 3 Graves patients without any nodule ultrasonographically, incidental thyroid carcinoma was found (5.7%). Consequently, thyroid malignancy rates were 16% in TMNG, 6.4% in AFTN and 12.6% in GD.

Thyroid carcinoma is common in hyperthyroidism and FNAB is a reliable method in diagnosis of thyroid malignancy in these patients. Additionally, incidental thyroid carcinoma prevalence is also high in patients with hyperthyroidism. We suggest that it is reasonable to evaluate nodules with FNAB in hyperthyroid patients prior to radioactive iodine treatment or surgical intervention.