First examination (first row of images):

Clinical presentation: A 39-yr-old man was referred for evaluation of a nodular goiter detected by chance on MRI examination.

Palpation: an elastic nodule in the left lobe.

Laboratory tests: TSH 1.59 mIU/L, FT4 13.4 pM/L.

Ultrasonography. The thyroid was echonormal. There was a multichambered cyst occupied almost the entire left lobe. It was a central-type cystic lesion with a minimally hypoechoic solid portion.

22 mL brown fluid was aspirated. Cytology resulted in benign cystic lesion.

Second examination a year later (second row of images):

Clinical presentation: The patient had no complaints.

Palpation: no abnormality.

Laboratory test: TSH 1.86 mIU/L.

Ultrasonography. The thyroid was echonormal. The cyst has not refilled. There was a moderately hypoechoic nodule with signs of cystic degeneration in the left lobe. The nodule showed irregular, lobulated margins.

Suggestion: ultrasound in three years.

Comments.

1. The solid part in the dorsal part of the cystic nodule was more echogenic compared with the ventral solid area. The difference is explained by the echo amplification of echo signal dorsal to cystic fluid.
   
2. The nodule' borders became irregular lobulated after the aspiration of cystic content. This is a relatively common situation.