Clinical data: a 19-year-old man was referred for an evaluation of hypothyroidism detected on screening.

Palpation: no abnormality.

Functional state: subclinical hypothyroidism with TSH 5.88 mIU/L, FT4 16.0 pM/L.

Ultrasonography : the thyroids were moderately hypoechogenic. There was a larger, more hypoechogenic area in the upper part of the left thyroid.

FNAC: disclosed Hashimoto's thyroiditis from the hypoechogenic lesion in the left lobe.

Comment. The horizontal view of the left lobe is not decisive whether the hypoechogenic lesion would be a nodule or not. However, on the longitudinal scan the situation is clear: this lesion is not a nodule but probably a more active focus of thyroiditis.