Thyroid fine-needle aspiration biopsy: which lesions should be biopsied before 131I therapy?

Suspicion of a neoplasm is one of the contraindications to radioiodine therapy in benign thyroid disease. The aim of this study was to present an optimal qualification scheme for fine-needle aspiration biopsy (FNAB) to rule out neoplastic lesions prior to radioiodine therapy.

4207 patients with hyperthyroidism were referred for 131I therapy in 2000-2006. Prior to 131I therapy, all patients underwent thyroid function assessment, radioiodine uptake, scintigraphy, and ultrasound. Fine-needle aspiration biopsy with cytology was done in 578 (13.7%) patients. Therapeutic radioiodine was administered to 3564 (84.7%) patients.

Malignancy was confirmed or suspected in 12 female patients (0.28% of all patients and 2.07% of patients who underwent FNAB). Prior to the study, cytology was done in only one patient. The diameter of the lesions was 6-28 mm. Cytology confirmed papillary carcinoma in 4 patients, follicular tumour in 6, and Hürthle's cell tumour in 1. There were indications for histopathology in one patient due to the presence of atypical cells. The primary diagnosis was toxic nodular goitre in 8 patients and Graves' disease in 4 patients. One of the patients with follicular tumour was referred for radioiodine therapy due to intolerance to thyrostatic drugs, elderly age, and comorbidities.

1. Thyroid scintigraphy prior to therapy is important for the choice of the site of FNAB. 2. Thyroid lesions in patients with nodular Graves' disease must be carefully investigated to exclude malignancy. 3. Preselection of patients for treatment of benign thyroid disease should be followed by cytology of the lesions at the Department of Nuclear Medicine.