Clinical presentation: A 29-year-old woman was referred for aspiration cytology of a thyroid nodule which was found on evaluation of vertigo and weight loss.

Palpation: no abnormality.

Functional state: euthyroidism with TSH 1.40 mIU/L, FT4 1.35 ng/dL, aTPO 10 U/mL.

Ultrasonography. The thyroid was echonormal. There was a cystic lesion having comet-tail artifact in the right lobe while a minimally-moderately hypoechogenic nodule was found in the left lobe. The latter showed signs of perinodular blood flow.

Cytology of the nodule in the left lobe resulted in benign follicular proliferation.

Comments. This is the typical presentation of a comet-tail artifact.