Clinical presentation: the 47-year-old woman came to a yearly follow-up examination because of hypothyroidism replaced with daily 100 microgram levo-tiroxine. She was well and had no complaints.

Palpation: both thyroids were moderately firm, but no nodule was palpable.

Hormonal investigation: indicated subclinical hypothyroidism with TSH-level 6.98 mIU/L, FT4 13.7 pM/L.

Ultrasonography: revealed hypoechogenic inhomogeneous thyroids. There was a more hypoechogenic area in the upper ventral part of the right lobe. The intralesional vascularization was increased. The size of this lesion was unchanged for 5 years. It corresponded to a more active focus of thyroiditis.

Clinical diagnosis: autoimmune thyroiditis, hypothyroidism.