Clinical presentation: a 35-year-old woman with hypothyroidism known for 13 years. She was on regular follow-up examinations. The TSH-level was normal (1.05 mIU/L) on daily 125 microgram levothyroxine therapy.

Ultrasonography: atrophy of the right lobe. The left lobe was composed of hypoechogenic nodule-like lesion.

Cytological report: Hashimoto's thyroiditis.