Clinical presentation: A 42-year-old woman was referred for aspiration cytology. A slowly growing nodular goiter has been known for 6 years. The goiter caused difficulties in swallowing in the last few months.

Functional state: euthyroidism (TSH 2.14 mIU/L).

Ultrasonography: There was a moderately hypoechogenic nodule in the left lobe with micro- and coarse calcifications. The nodule presented intranodular vascularity.

Cytological diagnosis:  suspicion of tumor with follicular structure including follicular variant of papillary cancer.

Histopathology: benign hyperplastic nodules.

Comments:

1. Because of the lack of sonographic signs of a capsule, i.e. because of the lack of halo sign and perinodular blood flow, the chance of a follicular tumor was low.

2. The cytological pattern itself was not reassuring. Besides microfollicular pattern, the presence of prominent nucleoli and grooves indicated surgical exploration.

3. This case was part of our prospective study testing the usefulness of the category AUS of Bethesda system. Considering the risk of malignancy, the patient decided to undergo surgery instead of undergoing on follow-up examinations.