Clinical data: A 34-year-old woman was referred for evaluation of a thyroid nodule which was discovered ten years ago. A small cystic nodule was found in the left lobe. Ultrasound was suggested in 3 years. The patient was planning a pregnancy and therefore applied for a checkup.

Palpation: no abnormality.

Laboratory test: TSH 2.16 mIU/L, aTPO 2.1 U/mL.

Ultrasonography. The thyroid was echonormal. There was an anechoic lesion in the lower pole of the left lobe. On gray-scale mode, this was not obvious whether the lesion was a cyst or a vessel while on Doppler mode, the mass proved to be a vessel.

Comment. In most cases, it is evident that a vessel runs like a pipe and it can be followed in the direction of its course. In this case, it was probably an enlarged vein, so we saw a discrete lesion and not a tubular formula.