Clinical presentation: a 57-year-old woman with fever and painful thyroid which had been present for two weeks.

Palpation: both thyroids were hard and painful on palpation.

Functional state: mild hyperthyroidism with TSH-level 0.02 mIU/L, FT4 27.1 pM/L, FT3 7.38 pM/L.

Ultrasonography: the thyroid was composed of hypoechogenic areas with blurred borders and decreased vascularization.

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

Suggestion: steroid therapy.