Clinical presentation: a 55-year-old woman has noticed a suddenly developed lump in her right lobe for 3 weeks. She was known harboring a cystic nodule for 3 years when 2.5 mL cystic fluid was aspirated.

Palpation: a not firm nodule in the right lobe.

Functional state: euthyroidism with TSH 1.07 mIU/L.

Ultrasonography. The thyroid was echonormal. There was a mixed moderately hypoechogenic-cystic nodule in the right lobe. The lesion presented various intranodular hyperechogenic granules including non-specific granules and more bright ones. The latter could be either comet-tail artifacts or microcalcifications. There were several moderately hypoechogenic lesions in the left lobe.

3 mL brown fluid was aspirated. Cytology resulted in benign cystic degeneration.

Comments. This case illustrates the difficulty of distinguishing between comet-tail artifact and microcalcification. The relevance of this differentiation lies in the consequences, the former is found almost always in benign lesions while the presence of microcalcifications increases the likelihood of papillary carcinoma.