Clinical presentation: a 41-year-old woman with fever and painful thyroid lasting for a month.

Palpation: both thyroids were hard and painful.

Functional state: hyperthyroidism with TSH-level 0.01 mIU/L, FT4 30.9 pM/L.

Ultrasonography: there were many hypoechogenic areas with blurred borders within both lobes. The vascularization was decreased.

Cytological diagnosis: subacute, granulomatous de Quervain's thyroiditis.

Suggestion: steroid therapy.