Clinical data: a 39-year-old woman was referred for evaluation of an autonomously functioning nodule known for years. The patient was euthyroid and did not get any medication for thyroid disease. She noticed a rapid growth in the size of the nodule in the previous several months.

Palpation: there was a very firm nodule in the isthmus.

Functional state: euthyroidism with TSH 0.86 mIU/L.

Ultrasonography. The thyroid was echonormal and presented several discrete hypoechogenic lesions. There was a large moderately hypoechogenic nodule in the isthmus. The nodule did not display halo but did perinodular blood flow.

Arpiration cytology resulted in oxyphilic follicular tumor.

Histopathology disclosed follicular carcinoma.